>>648225829didn't seppuku fail like ALL THE TIME? which is why they would have a second dude to cut off our head.
and I'm pretty sure drowning has a 100% lethality rate, since it's probably not considered drowning if you survive.
Slitting wrists (my preferred method if I ever decided to do this sort of thing) is hella lethal, since if you do it right and cut your arteries, you'll bleed out in a matter of minutes, probably pass out from drowziness before then.