He's bad at talking in front of others because of his stutter. 

Kaboku Kotani is starting high school, and he plans to do what he’s always done: go along with his friends, keep quiet, and not draw too much attention to himself. After all, it’s hard enough to get by with a stutter like his— why make things worse by standing out from the crowd? But then he sees another first-year, Hikari Wanda, dancing like no one is watching—or like she doesn’t care who sees her. It makes Kaboku wonder: Could he reach that same freedom? To find his way to Wanda, he does something he never thought he could: He joins the dance club. After all, every routine begins with a single step, right? Join Kaboku and Wanda as they freestyle their way to life and love!
 
(Source: Kodansha USA)
 
Note: Nominated for the Tsugimanga 2020 Award in the Manga Category.

Kaboku Kotani is starting high school, and he plans to do what he’s always done: go along with his friends, keep quiet, and not draw too much attention to himself. After all, it’s hard enough to get by with a stutter like his— why make things worse by standing out from the crowd? But then he sees another first-year, Hikari Wanda, dancing like no one is watching—or like she doesn’t care who sees her. It makes Kaboku wonder: Could he reach that same freedom? To find his way to Wanda, he does something he never thought he could: He joins the dance club. After all, every routine begins with a single step, right? Join Kaboku and Wanda as they freestyle their way to life and love!
 
(Source: Kodansha USA)