Hell's Paradise: JigokurakuHell's Paradise: Jigokuraku.

Hell's Paradise: Jigokuraku is a Japanese web manga series written and illustrated by Yuji Kaku. Set in the Edo period of Japan, the series follows the journey of ninja Gabimaru and executioner Yamada Asaemon Sagiri as they search for the elixir of immortality. Kaku wrote the series with the mindset of creating a setting including multiple pairs of people with unaligned interests thrown into an enclosed space and forced to work together.