NINJA BASEBALL KYUMA! (Kyuma!), by Shunshin Maeda. First published in 2004 and first published in North America in 2009.
PLOT:
For years, the young ninja Kyuma has waited in the mountains, training for the day when someone will need his skills. That someone turns out to be Kaoru, the captain of the Moonstone City Baseball Club team. He needs someone strong to help his ragtag team to win games, and Kyuma agrees to follow his new "liege". He may not understand the modern world (much less baseball), but he's ready and eager to learn and put his newfound talent to the test!
