That clue in yellow just cinches it. What Shuichi’s saying wasn’t even about him ‘revealing the truth’ of the cases. Not at the core of it.

This is about the whole, entire truth that Shuichi has been forced to repress until now. Every nagging doubt- how he got his title by ‘coincidence’, the anger of the person he sent down, how his actions led to Kaede’s death. Everything.

This is why he was so angry at Kaito for his well-meaning counsel- he had made the effort to drag his doubts from the dregs of his mind, and was in dire need of help to deal with it. He couldn’t just stew in it on his own, because it would just fall back into the unconscious again. This wasn’t what he needed.

You could say this is the most courageous that Shuichi has ever been, as he admitted he was afraid of facing himself. It would also explain why Tenko was so soft with him when they sparred, as she sensed he was in great pain.