[It doesn't matter if he does. His death has happened, it won't affect anyone except Shinpachi and Sano and they...have each other. It'd be okay still. But Yamanami? His death shattered the Shinsengumi. He can't let it happen again. He can't let him be murdered again.
He grabs the book again and throws it down.]
I already did!
[He stops and just stares at the book where it's lying, closed.]
action
He grabs the book again and throws it down.]
I already did!
[He stops and just stares at the book where it's lying, closed.]
...it doesn't matter. I already did.