Don't die! Umibouzu!! Love & vengeance of the magnum (Part 1)

Umibozu asks Ryo to take care of a young American girl named Kathleen Heywood. However, Ryo realizes that Kathleen is actually out to kill Umibozu in revenge for her father's death. The Arrival of known mercenary Dandy Jack complicates matters, and Ryo realizes that he may be the one who is manipulating Kathleen.