Where did Nagumo Tetora go?

He was so cheerful, so young, so full of energy. Full of life. But there he is now, sinking in the couch with a blank stare and his mouth shut close, not a single word to say. He looks so lost, so voided.

He's clearly struggling, but nobody thought the struggles would be stronger than him and would turn him into this.

"I'm gonna go to the bathroom, I need to refresh my face." He suddenly says, your face washed with a wave of grief upon hearing the monotony on what once was a cheerful voice.