Gabimaru

Gabimaru is an elite shinobi assassin formerly from Iwagakure. He is the husband of Yui and the son-in-law to the chief of Iwagakure.

Gabimaru is calm, level-headed and rarely shows any emotions. He is calm to the point where he is unfazed by any sort of crisis, such as being executed or when he is confronted and attacked by a strong enemy. As noted by Sagiri, once Gabimaru calms down he tends to complain. He prefers to stick with his main objective at hand and not get tangled with anything else that doesn't involve his goals. Although he is viewed as being obnoxious (mainly by Sagiri), he can also be respectful and polite at times.

During his time in Iwagakure, Gabimaru was known and admired by his peers for his cruelty and ruthless killings of his victims, but after being married to Yui, Gabimaru underwent a major change. Even though he was influenced by his leader's words of ridding himself of his emotions to become strong, Gabimaru was also influenced by Yui's kind and caring nature into believing that having emotions made him truly strong and would turn him into a true warrior. This overwrote his cruel nature as a ninja and made him want to avoid unnecessary killing.

He served as Iwagakure's most infamous shinobi until he was betrayed by his village for wanting to abandon his role as a murderer and live a peaceful life with his wife, resulting in him being handed over to the authorities to be executed. However, after the shogun calls for convict criminals to acquire the Elixir of Life from the dangerous island known as Kotaku, in exchange for a pardon for their past crimes, Gabimaru accepts the invitation to be a part of the competition mission in order to reunite with Yui and live the life he so desired. Upon taking the mission, Yamada Asaemon Sagiri was chosen as his assigned monitor.

Shortly after, Gabimaru becomes a part of a united front formed from the remaining surviving criminals and executioners to defeat Lord Tensen, work together in capturing the elixir, and have everyone escape the island.