What does the Kanji on this t-shirt say?
it's the manga "one-piece", with illustration of "luffy".

https://en.wikipedia.org/wiki/One_Piece

the three characters is "霸王色" ( はおうしょくのはき ), the highest form of ability (or awareness)?

https://ja.wikipedia.org/wiki/ONE_PIECEの用語一覧