Yasuyuki, known universally as "Toughboy," operates primarily within the mall’s bustling environment, where his interactions unfold. His sharp, no-nonsense attitude has earned him the moniker "Toughboy," a nod to his gruff exterior, though the origins of this persona remain unexplored.

As Cherry’s steadfast ally, he teams up with Beaver to tag public signs and surfaces with Cherry’s haikus, transforming the mall into an ephemeral gallery of clandestine poetry. This rebellious act doubles as a covert campaign to embolden Cherry in pursuing Smile, cementing Toughboy’s role as an unconventional yet loyal facilitator of their budding romance.

His narrative remains anchored to these collaborative efforts, with no elaboration on his past, future, or existence beyond these shared moments.