Bo-chan, also known as Bo Suzuki or Boo-chan, appears throughout the franchise as Shinnosuke Nohara's friend and a member of the Kasukabe Defense Force.

He is physically marked by a constant trail of mucus from his nose. His movements are typically slow and his expression generally calm or blank. Despite this outward demeanor, he reveals unexpected intelligence and occasionally offers insightful observations on artistic or mature subjects, contradicting expectations based on his sluggish behavior.

Within the Kasukabe Defense Force, Bo-chan maintains solid friendships. He shares a particular understanding with Nene Sakurada, and they consistently support each other. His interactions with Shinnosuke Nohara sometimes involve their unconventional ideas aligning. Bo-chan operates his own "detective agency" at kindergarten, reflecting his intellectual curiosity.

A significant transformation occurs when exposure to a supernatural artifact in India alters Bo-chan drastically. His characteristic runny nose vanishes completely. His expressions shift from placid to sharp and intense, while his movements gain sudden speed and aggression. In this altered state, rejecting Shinnosuke's help with the phrase "What do you even know about me?", he adopts a more tyrannical persona called "Bo-kun" or "Tyrant Bo-chan." This leads the Kasukabe Defense Force to seek a way to reverse his condition and restore his original self.