Sidooh

Tsutomu Takahashi sets this in the 1860s, the years right before the Meiji Restoration, when the old order was rotting and famine was everywhere. Two young brothers lose their parents and pull each other through hunger and plague by taking up the sword as a kind of religion. The "way of the samurai" here isn't noble. It's a survival cult, and the manga follows what that does to two kids who have nothing else. Takahashi draws with thick, scratchy ink and a lot of black, so the period feels filthy and cold rather than romantic. It's long, it's grim, and it never sells you the honor it keeps talking about.