Tarō Jirōmaru is a 31-year-old novelist who frequently stays at the Kissuisō hot spring inn. He proclaims his works will change the world, though they are erotic stories secretly based on the inn's staff. Initially, he believes only Ohana Matsumae knows his secret, but Sui Shijima, the inn's owner, is also aware and permits his stays despite the content.

Previously a manga artist, one of his works inadvertently inspired both Minko Tsurugi and Tōru Miyagishi to become chefs. His manga career ended after only a few published volumes due to insufficient skills, leading him to shift to novel writing. Financially unstable, he accumulates mounting debt at Kissuisō and cannot pay his bills. When his secret writing and financial issues are exposed, he attempts to flee by stealing an inn vehicle but is caught by the staff. Nako Oshimizu rescues him from drowning after he jumps off a seaside cliff in despair.

Following this, he begins working part-time at Kissuisō to repay his debt. His duties involve laborious tasks around the inn, and he is officially listed among the staff as a "laborer." He habitually exaggerates or fabricates stories to make his life seem more dramatic, a trait that diminishes others' respect for him and sometimes results in punishments from the staff.

In *Hanasaku Iroha: Home Sweet Home*, he reprises his role as a supporting character. His presence across all media remains consistent with his established role as a debt-ridden writer contributing to the inn's daily operations while pursuing his creative work.