Set in the Edo period, Kanou Toshu studied medicine in Nagasaki and lives on the outskirts of Senju-juku . He is also a master of the Mugai Ryu sword style. Although he has skills in medicine, he is also a big drinker and often drinks all day and falls asleep, or drinks at night and does not go home. He does not charge for treatment and medicine costs from poor patients such as tradesmen and farmers, but occasionally he'll buy their produce or drink with them. When he senses injustice by the rich and powerful, he takes matters into his own hands and doles out justice as he sees fit.