Well, Kanji ends up being the quieter one, because Jack's version of sneaking up on enemies is to rush into view and think later. In his defense, he's used to being stormed by crowds.

Lucky for Jack they run across a U-Man who is both very new to battle and possession of fire powers, which Jack is very used to. By the time Kanji catches up to him he's shoved the man onto the floor and is in the middle of beating him to dead with the wrench. Which... with a wrench of that size, probably happened around five whacks before Jack actually stops.