After confessing to his long-time crush upon graduating middle school, Rentarou Aijou is rejected for the 100th time. Devastated by the constant heartbreak, he visits a matchmaking shrine and offers a prayer for love in high school. Much to his surprise, the god of the shrine appears before him and promises him one hundred soulmates.
Initially, Rentarou is doubtful of this divine intervention, but his skepticism quickly fades when two of his soulmates, Hakari Hanazono and Karane Inda, confess their love to him on the very first day of high school. However, there's a dark twist to the deal that the god never revealed to Rentarou – if any of his soulmates fail to form a relationship with him, it's curtains for them.
Confronted with a life-or-death situation, Rentarou decides to date all one hundred of his soulmates, inspired by his enormous heart that can accommodate them all. Thus, he sets out on an unexpected journey to make the most out of his new high school life, with the Rentarou family growing ever larger!