Dōdō's mother became a problem gambler when she began aware of her husband's affair. Eventually Dōdō's father left the family, excusing the debt her mother had accumulated and her unstable mental health which required long term clinical care in the hospital. Being taken care by his maternal grandmother, Dōdō fell in love with his classmate. His best friend volunteering to be the matchmaker, ended up dating the girl in Dōdō's place, even though the girl was originally in love with Dōdō's friend. Saddened by his failed family and first love, Dōdō made a wish to escape to an unknown territory.
Dōdō enters the Borderland 4 days after Ryōhei Arisu has joined the Beach society. He is attracted to a lit commercial building upon nightfall, which turns out to be the arena of the Four of Hearts. After being betrayed by a female player, Dōdō is enraged. He sheds crocodile tears and lies about the answer during the question that he is knowledgeable thanks to his sick mother. He regrets it after his dishonesty causes the death of the previously cheating player, but another hooded player helps Dōdō win the game first and Dōdō in return searches the correct answers for him to survive the game. This hooded player turns out to be Arisu.