Four and a half stars for an isekai.
Shortly after this volume starts, the protagonist, who is a forty five or something years old guy who is currently inhabiting a twelve or so years old body (because he got isekai-d from Earth into a fantasy world, where he was born again retaining his memories) comes across the closest thing to rice in this fantasy world so far. He drags his party members on a quest mostly to figure out how to cook rice-related dishes that would properly remind him of home. Along the way he receives another visit by the creepy, flamboyant so called man-god, a supposed deity that has forcefully adopted our protagonist as his disciple. This man-god reveals to Rudeus (our protagonist) that the mother of his half-sister, as well as the sister herself, are being retained in the royal palace of the kingdom of Shirone, incidentally where Rudeus' master, and favorite, Roxy Migurdia had to flee from, because the prince she was teaching wanted to kidnap her into sexual slavery. However, the man-god has kept for himself that Roxy is currently far away from Shirone, because she's travelling through the demon continent in search of Rudeus. Our protagonist believes that he's going to see his beloved master again at the palace.
At this point, Roxy has put two and two together and has understood that her and Rudeus passed each other on a port town, and that they are currently far away from each other. Her focus shifts towards finding other members of Rudeus' family. She's being accompanied by some dwarf and a very horny elf.
Rudeus was told by the man-god not to tell his real name to the local guards nor to anyone at the palace in general. He fucks it up in a letter, but he only gets the consequences later on. His half-sister Aisha had been trying to sneak a letter out of the palace, but some guards were after her. Rudeus saves her, and puts her in the care of his party members. However, Rudeus avoids admitting to his half-sister that he's his big brother, because Aisha had gotten in her head that his big brother was a huge pervert and that he might go as far as attempting to sexually abuse her six years old self. And to be fair, she isn't that far off: during the rescue, Aisha had pissed herself. As Rudeus changed her clothes and handled her pissed panties, he treats us with a long monologue about his surprise because touching and smelling his six years old half-sister's panties soaked in piss doesn't make him hard. Those two bombs really did a number on the Japanese.
Practically nothing in any fictional story I have come across bothers me (except if it's politics I disagree with), but apparently my line is at wanting to get hard through your six year old sister's piss-soaked panties. Plenty of stories inspired in some way or another by "Mushoku Tensei" have been adapted into mangas and animes, but MT had remained untouched, and all the weird sexual stuff is the only reason. The anime wasn't shy about including many of the most controversial aspects of the light novel series, including the fact that the protagonist was jerking off to loli hentai, and even added more perverted stuff on top of it, but I have a hard time believing they will include this moment.
In any case, when Rudeus enters the palace and meets the prince whom Roxy used to teach, he finds out that he's holding Lilia, the mother of his half-sister, hostage, and the prince quickly imprisons Rudeus in a cell that nullifies his magic. Interestingly, though, we are introduced to a new character that ended up being quite compelling. It's another one of the princes of that kingdom, a lanky, nerdy-looking guy obsessed with figurines, and who had smelled that Rudeus had been making some of the best he had come across. Saying that the guy is obsessed with figurines is an euphemism: the guy beheaded one of his infant brothers as well as his wife because he wasn't occupied with figurines at the time. He has some sort of inborn superpower that makes him unbelievably strong, and although the rest of his family feared him, they considered him too much of a secret weapon to banish him. The guy learns that his hated pissant of a brother, who wanted to lure Roxy in to turn her into his sex slave, was behind imprisoning Rudeus, and this nerdy prince captures the worse prince to force him to release our protagonist. After a whole mess involving other more rational princes, Rudeus gets released along with his half-sister and his half-sister's mother, and both the nerdy prince and the bastardly one are banished from the kingdom.
The six years old half-sister realizes that his big brother is kind of cool, despite the whole wanting to masturbate with her piss-soaked panties, and promises that one day she might serve him or whatever. Her mother, who is a bit out there, had promised herself that she was going to repay Rudeus by offering her daughter as a maid.
My least favorite part of this volume involves Rudeus meeting Lilia, his half-sister's mom, again. Lilia started disliking Rudeus when he was a baby, because due to his pervertedness she believed that he must have been possessed by a demon. But after Lilia seduced Rudeus' father and got herself pregnant, Rudeus interceded to prevent Lilia from getting exiled from their household, therefore saving not only Lilia but also her unborn baby. There must have been many complicated feelings between Lilia and the protagonist, but their meeting years later was disappointingly dry.
Rudeus and his party members (Eris, a fifteen years old, violent redhead whom Rudeus wants to do sexual things to, and who received Rudeus' lessons; Ruijerd, a badass demon warrior whom everybody else fears) are getting real close to the endpoint of their journey, and therefore of this arc. This arc started when some mana disaster or another destroyed the whole region were they were living, and its inhabitants were teleported here and there all over the world. Rudeus had promised that he would return Eris to her family back at the disaster zone. Before they reach it, though, they need to pass through some dangerous pass that's infested with a kind of dragon. However, dragons don't bother our party at all. Instead they come across the Dragon God, a guy who is the second strongest in the world and who seemingly knows every existing technique, magical or otherwise, including seeing the future. However, our protagonist doesn't seem to appear in the guy's predictions, probably because Rudeus belongs to another world. Upon learning that Rudeus is a sort of disciple of the man-god, this Dragon God straight up murders Rudeus, who dies for a moment. However, some mysterious girl who was following the Dragon God asks him to save the protagonist, and Rudeus and his party members are left distraught by how easily they had been obliterated.
Ruijerd, a demon warrior belonging to a hated race, learns through Rudeus that their terrible reputation is due to a curse that's fading away. That satisfies him, although it's hard to consider this a win for Rudeus, who had made one of his main goals to clear the reputation of Ruijerd's tribe. In any case, minutes away from the Fittoa disaster zone, Ruijerd announces that he's done his job and that he's parting ways. Eris and Rudeus rejoin not only Eris' family's main servant, but also fan favorite Ghislaine, who had found her way back home. Things are fucked, though: both of Eris' parents are supposedly dead, and also her boisterous grandfather. The grandfather, a local ruler, had gotten beheaded by some higher-ups because someone had to take responsibility for the mana disaster that nobody knew why had happened.
Eris isn't sure what she wants to do now, except that she is sure she wants to have sex with Rudeus. That night she offers herself to him. Rudeus resists, probably because he's mentally forty seven and she's fifteen, but Eris asks him seductively whether he wants her to become his little kitty, and Rudeus loses his mind as well as his virginity. Eris was a virgin as well, not that it particularly matters in this case. However, Eris didn't feel that she could stay around, because getting defeated by the second strongest in the world showed that she had too much to learn and that she was holding Rudeus back, so she takes Ghislaine and leaves to train and shit. Rudeus finds himself fully alone.
Meanwhile, Roxy has a drinking contest in the demon continent that happens to include the demon empress Kishirika Kishirisu. Roxy was nice to the demon empress, who is known to be very grateful with those who treat her well. As payment, Roxy asks the empress to reveal the locations of the remaining members of Rudeus' family. We learn that Rudeus' mother is somehow inside one of the world's most dangerous labyrinths, but apparently alive. Our protagonist doesn't know this, though. Roxy's party splits in two. The horny elf and some local demon lord that Kishirisu is betrothed to will inform Rudeus of these news (incidentally, the fact that the guy's dick is too big and Kishirisu's pussy too small is a plot point), and Roxy and his dwarf party member will locate Rudeus' father to inform him as well.
This is pretty much where this volume ends, although I have read a bit of the following one and I'm not sure where the beginning of the next arc falls. In any case, the whole mess of the Fittoa mana disaster has finished. It was one of the oddest arcs in any Japanese series that I have consumed in these last few years. They didn't intend to achieve anything in particular beyond returning home, and all that happened along the way had to do with learning about the world, getting stronger and getting to know each other better. I did enjoy it a lot, but I wonder if I would have if I didn't care a lot for the characters.
In any case, it's "Mushoku Tensei" being itself. If you haven't been thrown off by plenty of stuff it does, you are likely along for the ride until the end.