Bayern Munich president Uli Hoeness has told kicker Joshua Kimmich's form has benefitted since speculation about his future was ended.
Fixture list for the new season gives new Leverkusen coach Heiko Herrlich the toughest possible start.
Kamada has scored three goals and set up a further two in 16 matches in Japan in the current J-League season.
Coach Domenico Tedesco, 31, replaced Markus Weinzierl earlier this month and has now officially started work.
Klinsmann, the 20-year-old son of former U.S. head coach Jurgen, will join the Europa League side for their preseason training camp.
Bayern Munich president Uli Hoeness says the Bundesliga champions are in the business of buying young players to strengthen the side.