The Mail Order Life of a Man Around 40 in Another World

I think, there is still a slim chance, despite manga being dropped, because the anime itself and intro\outro contain a lot of references to the further novel events. The exception beight Komatsu-robot. Kenichi later upgrades his Komatsu with a huge adamantine blade bought from dwarves, which crafted it just to show-off at their store. Hand “rocket-punch” is a reference to Anemone’s attack using her golem magic. But Kenichi never constructed a robot-like machine.

After the battle with the lesser dragon in the palace, when the dust has settled, 
a messenger arrives with a message that an important transport artery of the kingdom 
in the mountain pass has been blocked by a landslide. 
The king tearfully asks Kenichi for help, as does Princess Lilith, who goes with him 
to personally supervise the process and prevent Kenichi from possibly defecting the kingdom. Kenichi reluctantly, agrees to help, but bears resent to nobles and queen.

The queen remains in the palace (thus, the anime follows the novel, albeit swaps some events (for example, Kenichi drives in heavy rain and discovers the bridge destroyed by flood during his travels to the capital, not after, as seen in the anime final episode and he was granted noble status much later in the novel) Possibly done to cut anime time while still having a possibility to add those events later.
 
Nyamena, being in awe by Kenichi’s prowess when he killed the lesser dragon with a single blow of his Komatsu, instinctively goes into her heat cycle prematurely (they intinctively crave for strong partner). Kenichi, on Myare’s advice, had to give her strong alchohol for her to pass out and sleep it off (this is how female beastfolk usually cope with their cycle to avoid being “manhandled” by the males. As they as basically defenceless in that state.)
On Myare’s advice, Kenichi had to become Nyamena’s partner for the night, as this period is described by her to be unpleasant and painful for beastfolk without a partner. As a result, even though he put on thick leather jacket for protection, he was badly scratched and bitten all over, but he endured it. Anemone healed his wounds in the late morning. 
Afterwards, Nyamena was very ashamed of what had happened, although she remembered little of it herself and was shocked at how strong the effect of the cycle had been. (Probably, because you don’t see dragons defeated everyday). Much to her relief, Kenichi embraced her as she was, along with Myare. From that moment on, Nyamena essentially became Kenichi’s lover too. Though Myare and Nyamena continued to bicker from time to time, they were essential as scouts and as combatants.
Kenichi teased Nyamena with memories of that night, which caused her to run away in shame, or, as Myare said – “Torako’s self-destruct, nya”. – This part seems to have been cut from both anime and manga.

While clearing the rubble blocking the mountain pass, the group encounters and defeats a wyvern. 
Princess Lilith finally aknowledges, that Kenichi actions and achievents to help the kingdom are worthy of a blessing and grants him the abilities of a holy knight (through a kiss, of course). This is an ability that a person of royal blood can bestow upon the chosen one once in their lifetime. 
Kenichi gains healing abilities and resistance to physical damage and magic. Using this abilities induces hunger, which he copes by bying energy bars. When healing power is applied to a healthy person, they begin to experience an effect similar to ecstasy. By coincidence, the same day he gains his powers, he spends a night with Myare, because she began to feel frustration caused by self-restraint. Unknowingly and being unable to control his holy knight healing powers yet, he takes Myare over the moon and beyong, much to Nyamena’s envy (she was passed out drunk in a separate tent after the battle, because, you guessed it – wyvern defeated by hers truly. Passed out drunk along her were three other beastwomen which were hired as guards by merchants caravan). Later he buys a special magic ring to suppress his powers at first and later learns to control them.

Before returning to the palace, Kenichi learns that his Isekai’ed compatriot Akira, whom he has heard so much about, is staying in a nearby town in a neighboring kingdom (which later revealed to be having same holy knight abilities). 
With the princess’s permission and assistance, he heads to the town and locates Akira (who already has his own harem (sigh) and even adds male elf later (yuck) (male and female elves are described as looking feminine). 
His main wife is Reiran (whom he often refer as sensei), a legendary magician with an even more legendary bust size. Kenichi helps Akira and his family (harem) defect their kingdom where he was ruthlessly exploited. Lilith negotiates for Akira and his family to gain asylum. Along with Reiran, there was female knight Clementina (to quote Akira – “A knight, who lost to my d***”), merchants daughter (if memory serves) Annerose and a cat beastwoman Myaa, whom Akira bought out from brothel. And later he adds a male elf Tsitsura. Akira has been literally running away for weeks from Reiran when she learned about his endeavours with elf, but according to him “they reached an understanding”.(A LOT about Akira and his endeavours I personally had to overlook. But in general, he is not a bad guy at all, albeit foul-mouthed).

Upon returning to the palace, where Kenichi was to be awarded, another skirmish ensues. Nobles were furious upon hearing, that princess bestowed a blessing without consent.
Princess Lilith, no longer wishing to have anything to do with the nobility, announces her desire to renounce the throne and leave the palace with Kenichi.
Kenichi confirmes her wish. Upon hearing that, the queen finally loses her composure and attacks Kenichi with a sword. 
He is saved by his ability as a holy knight: resistance to physical attacks.
Kenichi had anticipated this situation and prepared himself. Akira helped to restrict the knights, while beastfolk were aiding Kenichi. He is enraged by the queen’s and the nobility actions in general.
As a result of a lucky chance (she slipped on a banana peel, thrown by Kenichi as he was replenishing his holy knights powers eating banana, creating an opening for him – go figure) the queen was doused with bear pepper spray, paralyzed with a stun gun, and, just to be sure, Kenichi lifted her in the air (holy knoght’s strength) and used his healing ability at full power, which completely incapacitated her.

Aftermath, the king assured Kenichi that the queen had acted on her own and that neither skirmish had been planned. 
He also promised full amnesty and a reward. Kenich figured him to be a mere figurehead in the capital, wishing just to leave the capital ASAP.

During a dinner outside the castle, Kenichi and the others are shocked to see the queen in front of them. 
She falls to her knees and begs Kenichi to take her with him. The details of her behavior are revealed. 
She had been trained to be a queen and act accordigly as a noble since childhood, and she hated it. 
Despite being beautiful, her intimidating presence scared th s*t out of Kenichi at first. But much like Anemone prayed for God to come rescue her and feed her delicious food everyday, queen Amaranthus dreamed that a knight would come and “rescue her from the dark room”. She has been fighting her own battle with the nobles and anti-royalist faction alone her life.
At first, she was very happy to learn that an extraordinary magician had appeared nearby. Crushing bandits, foiling anti-loyalist plans, including saving her from cursed vase in her room.
But Kenichi was friendlier to Lilith, than her, and out of jelousy, the first clash occurred. 
And after Kenichi announced his intention to take Lilith as a reward instead of her, it completely broke her.

After Kenichi rejected all her pleas, even after she obeys humiliating orders from him, calling her phycho, (he was still very angry at her for endangering his life and his family, even costing several knights their life during the lesser dragon skirmish), she took out a slave binding artifact and made a ritual, effectively making her a slave to Kenichi, without his consent. She refused to undo it, even after Kenichi, knowing that she as a slave cannot disobey, ordered her to return to the King, she disobeyed the order, causing her excruciating pain by the slave contract. As a slave, she now could not neither harm, nor disobey her master – Kenichi. To stop her suffering, Kenichi had to cancel the order. This further complicated the situation.

In the end, Kenichi bargains for the status of margrave and a large territory near the lake where his house was located (near Astrantia). 
In exchange, he takes away with him the problematic queen and princess, so the king could finally choose concubines and continue his lineage (the queen did not want to have children with the king and was against concubines for many reasons, including blood related).
Later, Lilith admitted she was not aware of her stepmother’s sufferings. She pleaded Kenichi to not leave her stepmother behind, as she felt indebded to her for raising her like her own, despite the princess and queen not being relted by blood.
In time, Amaranthus becomes powerfull ally as a combatant, advises Kenichi about governing and kingdom, and becomes a lover. Kenichi speculates, that somehow she bestowed holy knights powers on herself, because of how absurdly strong swordmaster and a fighter she was, able to defeat several beastmen with bare hand effortlessly. She is also seen in the anime intro, wearing red hood.

Kenichi establishes the county of Hamada, with Sakura as its capital. He has many more adventures on land, at sea, and in dungeons. 
Many people leave the kingdom capital (chef, magicians, servants) and enter the service of the county of Hamada. 
Beastfolk and dwarves also flock to the county.
Including old acquaintances. Amana (elderly woman trader, which Kenichi met in Dahlia) becomes a head of a children’s orphanage in Sakura.
He encounters various tribes of elves during his travels 
(who turn out to be immigrants from another planet who have abandoned technology in favor of living in harmony with their surroundings, albeit isolated from others).
Bell (Or Vel, the forest cat) is revealed to be a princess Celestis from long fallen kingdom (she undergo a transformation as a side affect of escaping a lich through summoning magic space (similar to item box, but living beings risk turning to monsters there, which cannot be undone. Due to Celestis blessing, she did not turn to monster but to forest cat). This explains her exceptional intellect for a cat and reason why Kenichi is able to understand her.
Kenichi can see her true form in his dreams, where he rests on her lap. (there’s also a refence of that in the anime). Her past is revealed to Kenichi upon by that same lich in one of the dungeons he discovers on his land. (I think it is the same lich they defeat in anime intro)
He later also rescues another forest cat – Kage.
 
And as for the harem by the end of the novel:
Lilith becomes first official wife (since, according to the law, a noble cannot have a wife of lower status. Hence, Primula was a no-go. And Lilith, despite renouncing the throne, could once again become the wife of a noble and was skilled as a politician, while Amaranthus could never ever gain noble status again because of her slave contract nor did she wanted to).
Primula becomes the second wife (or concubine). She works at Marlow Trading Company and as financial advisor.
Amaranthus – as a slave and lover\mistress (she refuses to dispell her slave contract, she just wants to be near Kenichi)
Myare and Nyamena as beastfolk mistresses. With the best glossy fur in the whole kingdom (because he brushes them every day).
Kanan as concubine (yes, THAT countess). She divorced her husband and now works at her clothing shop. Being a concubine of a margraive was her wish and a solution to avoid backlash for her parents (which are also nobles) after divorce.
Setera – a 5000 year old (hag) elf (sorry, I don’t remember for sure, but I think she also had a relationship with Kenichi).
Anemone – as a stepdaughter. By the end of the novel, she had grown noticeably.
There may have been others, but they were too unremarkable to remenber.
Kenichi also added male cat beastfolk to the family – Aoi, but only because he was calico male, a very rare color type. (a rare pokemon to collect, though I had my fears, especially after reading about Akira’s endeavours)
Aoi was weaker and smaller than most male beastfolk, but had exceptional hearing.  

(Sorry, but I won’t reveal these, you may read at least the last couple of chapters yourself 🙂 )
At the end of the novel, Kenichi and Akira finally learn how they ended up in this world. 
How they got their abilities, including Kenichi’s online store.
Why Akira had most bizarre ability to create mayo with his fingers and separate substances (Kenichi used Akira as endless supply of diesel fuel because of that)
How they could or could not return home.
Why they could not have children, how they could fix it and what was the cost.

Novel ends, when Lilith gives birth to Kenichi’s heir. Primula is due to give birth too. Everybody cheers. Kenichi is finally feeling his slow life in another world has begun.
(Because, when children are born, the adventures end and everyday life begins 🙂 )