Zeno Zebia grew up with little to show for anything she did. She always drew the short end of the stick, made poor decisions, and was raised by a grandma that forced her to take the worst adventuring jobs. Tired of that life, she ended up drawing the legendary sword Excalibur and became a hero. She then set off to slay the Devil King and change her life for good.
The problem? That Devil King is actually a one-year-old.
Tonchi Kataoka’s How to Train Your Devil is set in a fantasy world that is general RPG/adventure parody and general ecchi tropes. See, the Devil King that’s one-years-old? He’s actually a mature one-year-old named Grull Gurrehl that’s an absolute pervert. He acts like a baby — needs to suck breasts, is unruly, etc — but is far too advanced in speech and perversion to not be thrown in jail.
He technically was jailed though: after Zeno realized she couldn’t kill a baby, she and Grull were brought to trial by a hopelessly shameful priest and various knights. Despite her learning that Grull is a sex fiend, Zeno believes he can be trained to curb this behavior. The priests and knights eventually agree, and end up “tricking” those two to sign a contract — Grull can’t actually commit any sex crimes or perish, and Zeno must help him do a lot of good deeds or perish.
So in swift order, the Hero is essentially back to being an Adventurer…
With a number of typical ecchi tropes, this ain’t for everyone. For example, what happens when you have two girls at a hot spring and a plant-based monster sprouts out of it? And what happens when a naked chick that can turn into a half-bat shows up at your doorstep and wants to straddle you…when you’re a one-year-old Devil King? It’s not a hentai, but the hentai tropes are around and kicking! It does its best to parody those common setups, but overall, it’s more likely to turn people away.
The only reason you’d even consider this manga is playing it straight is mostly due to the art. Kataoka’s characters express a number of emotions, from shock to terrified to why to stupefied really well. It was a trip when Zeno and Grull were assigned their first adventure, and they ended up meeting a girl who…is just a chuuni! And then that girl gets saved and falls for Zeno. Makes sense that the only one who realizes the girl’s chunni nature was the Devil King. But that was paneled well and drawn interestingly enough.
Also this manga has a chapter where Zeno’s grandma shows up, and it is the best. She’s incredibly strong, tricks the Devil King, and also tricks Zena (who on sight ran away from her). The faces for all of them in this chapter are great, and it sure shows off Kataoka’s range, whether the characters are stationary or take action. In general, the story is simple enough to where it shouldn’t get into major trouble plot-wise — Zeno has to be the Devil King’s mom to not die, the Devil King has to do enough good deeds and stop being a sex offender to not die. Simple, see?
From there it’ll be whether you can deal with how this manga handles that. Most of the characters are ladies, and we have one scene where, to reveal that the Devil King is a degenerate, a woman shows up and teases that she’s not wearing any underwear. I’ve already explained the classic tentacle trope that we all know, and can suspect future volumes will continue playing this game. If none of that is tolerable, this is a skip. The parody of tropes and strong artwork does make How to Train Your Devil worth a look for everyone else if you’re in need of an ecchi manga.