Gravitation EX 

In order to heal the wounds in Eiri Yuki's heart, he and his vocalist lover, Shuichi, travel to New York to visit the grave of Yuki's first love and tormentor, Yuki Kitagawa. They discover that the first Yuki has left behind a young son, Riku, and so the odd couple take the boy back with them to Japan. When Shuuichi receives a kiss from nutty rival band leader, Ryuuichi, Yuki flies into a jealous rage, and he and Riku disappear, leaving Shuuichi to search for them in vain.