I quite liked this show's first episode in 2021, but back then didn't keep watching. The simplistic art resembled a children's picture book, with the hero (Bojji) who's a tiny boy who makes a cute friend. It looked like a kiddie show. I didn't give enough weight to the fact that it aired in the late-night noitaminA block for mature viewers.
My assumptions were wrong. Yeah, it looks childish. However, its world contains genocide, disease, poverty and bloodshed. Wars are fought for cynical political reasons. Fights are brutal. Backstories are horrific. Bojji is deaf and mute, while the inhuman shadow creature (Kage) who'll become his best friend is one of the last survivors of an assassin species. In past wars, women and children were executed in disgusting ways. Being in a royal family means assassinations, either planning them, being ordered to carry them out or being on the receiving end. Also, your death was probably ordered by a close family member.
Even the fantasy elements are darker than they look. Kings might be giants, easily ten metres tall... and they're capable of the extreme omnivore tendencies of fairy tale giants. (Also, a male giant can father children with a normal-sized human wife. Don't ask how they managed that.) It's possible to do literal deals with the devil and to arrange to extend your own life through bodysnatching and/or the pseudo-vampiric murder of your son.
Bojji is technically a full-blooded giant, but he's tiny. When standing in his father's hand, he looks like an insect. He is, though, determined to fulfil his royal destiny and be heroic. He's also a thoroughly nice child, being unaware that the traditional behaviour of royalty is to be an evil bastard and that his own family demonstrates that. He's adorable. I loved him, especially given the brutal world he's up against. He looks, thinks and acts like the protagonist of a far more innocent series.
SEASON ONE (23 episodes, 2021-22)
Episode 8 was where I realised that this was WAY harsher than my expectations. Parents would complain if this aired in a children's TV slot. This episode has an assassination plot in the royal court and the impending execution of a nice chap, while a dead father bodysnatches his own son and sends the son's soul into blackness.
Mind you, earlier episodes already had the assassination of a child (ordered and carried out) and a hard guy severing his own hand.
I'd have loved Bojji even in the kiddie show where he belongs, but I went berserk on seeing him triumph in this terrifying world. He can beat giants in combat. He's a giant himself, technically. His size is all wrong, but he compensates in speed. More importantly, though, the narrative isn't just being horrible for its own sake... although evil things have indeed happened. Especially to mothers. There's a public throat-slitting of a child. However, people you might have written off as mere villains can have a sympathetic or even heartbreaking side, e.g. sincerely trying to be a good mother even to someone they're not related to. Also, unexpected people have learned sign language for Bojji's sake.
"Motherhood" is one of the show's themes, actually. That dead mum talking to her son... she got to me. Emotional. Anyway, this season's fantastic.
SEASON TWO: THE TREASURE CHEST OF COURAGE (10 episodes, 2023)
...but this is filler. I enjoyed it, but it's a collection of shorts before, during and after Season 1. Mind you, it's experimental in its own way, with paper cut-out art styles in episodes 8 and 9.
OVERALL
Don't underestimate the show's kiddie side. The art style will wrong-foot you, being more akin to, say, 1950s manga than a modern show. Queen Hiiling has torpedo boobs, but the show couldn't have been less salacious had it been from Disney. The cast is memorable, both in characterisation and in wild character designs. There are even pun names. King Bosse is the boss, Queen Hiiling has healing magic and Prince Bojji's name is a combination of "ouji" (prince), "bocchi" ("alone, isolated") and half of Daidarabocchi (a giant from Japanese legend). The other half is his brother, Daida.
Sometimes it's funny. Prince Despa is a laugh. Sometimes it's horrifying, but I loved Bojji, Kage and their friends. (Although the latter isn't a clear-cut category and can contain surprises.) This one's special. I completely misjudged it... but that's part of its power.
An anime film has been announced. I'll keep an eye out.
Could you show this to children? Hmm. I suspect the right child would go nuts and love it, but it would definitely be too much for some others. Also, you'd need either a serious discussion with their parents or to ensure that they never knew you'd shown this series to their offspring...