Matsukichi lives in Maison du Wish, a shared apartment building housing university students preparing to retake failed entrance exams. He is one of four central residents, alongside Yurume Aida, Sae Kawano, and Kumi Tanaka. His defining physical features include glasses and facial hair.

He exhibits patterns of heavy drinking and is prone to sleepwalking. During these episodes, he sometimes prepares tea or attempts elaborate tasks while asleep. Matsukichi joins the group's daily routines and unhurried adventures, such as communal efforts to beat the summer heat, shared meals, and decisions about household chores like cleaning a moldy rice cooker. However, he frequently avoids responsibilities or work, fueling the generally lax and unproductive atmosphere among the residents.

The arrival of Sae's younger sister temporarily disrupts the apartment's established rhythm, challenging the residents' entrenched idleness. Matsukichi, like the others, encounters this pressure to alter his slacker habits, though his fundamental behaviors and role within the group persist throughout the depicted events.