- "Welcome! To the utopia, the 'Beach'! I understand well. You guys are seeking 'answer'."
—Boshiya in the manga Chapter 15.
Takeru Danma with the alias of Boshiya (帽子屋, lit. "hat merchant") is a character first appears in the Beach arc. He was the leader of the Beach society and represented the "idealistic sect" of the Beach residents, as opposed to Aguni's "martial sect".
Danma and Aguni had been sworn friends 10 years before they entered the Borderland when they were 16 years old. Danma affectionately addressed Aguni "Mori-chan" for watching his back while fighting other street thugs. Later he worked as a gigolo in the Kabukichō red-light district. Just before entering the borderland with Aguni, Danma succeeded his deceased father's hat shop, hence his later alias "Boshiya".
After winning few games, Boshiya realizes that the Borderland is unchangeable. Inspired by Gandhi's motto, "be the change you want to see in the world", Boshiya convinces Aguni, An, Kuzuryu, Mahiru and Niragi to join his plan to establish his utopia. After the Beach attracts more immigrants for food and leisure facilities, suicide, drug abuse, violence and sexual assault becomes more common. Boshiya concludes that the Beach residents need an answer to fulfill their purpose by fabricating the false method of leaving the Borderland via collecting the complete suit of cards. The truth of his lie is only shared with Aguni. As time has passed, Boshiya is no longer able to differentiate his false hope from reality, he kills his residents for not offering their cards and amends the Beach rules for executing traitor.
Just 1 day before the Witch-Hunt game commences, Aguni calls Boshiya to an isolated bridge just outside of the Beach resort for bidding farewell because Boshiya is no longer the person he once knew. Believing the leave is a grave treason, Boshiya points his gun at Aguni's head, but Aguni reflexively shoots back and sends Boshiya's body below the bridge. Aguni quickly finds out Boshiya's gun is not loaded and he actually desired death in his best friend's hand. Aguni is devastated and decides to kill all Beach residents and himself during Witch-Hunt in order to bury their false hope for good.