What to read after Oyabun?

Cid, a Filipino musician who defied being away from a loving and protective family, dared to go to Japan during the time when the story of Maricris, a Filipina entertainer who was allegedly killed by a yakuza by plunging his sword to her vagina, was all over the news back home. He just wanted to work and earn his own money. What better way of doing it than to get paid doing what he enjoyed doing the most — singing." With another singer, Maria, they went to Japan as a duo and performed in cities from Tokyo to Chiba and Nagoya. Japan was flowing with money! The place had a way of entertaining you! The delicious foods, the drinks, the drugs (if you're into it), and of course, the tips! But without intending it, he got involved with Filipinas who had relations with yakuza. His life changed. He listened to stories told by another yakuza about his boss and his brothers. Every story left him with fear and the urge to get away as far as he could go. But he has to save Maria, who got herself involved with the boss. He won't be able to live with himself if he just left without taking her. But the task was not an easy one. How can a musician who hasn't learned any martial arts and instead spent his days playing his keyboard outsmart an evil man?