Asami and Fei Long were never together in the past. But I think Fei Long had feelings for Asami (I think, not sure now, it's been too long since this manga was released ╥﹏╥ ). And Asami just thought of Fei Long as a friend. Hope this helps.(⌒▽⌒)
1) The characters are heavily involved in underground business but they're not exactly Yakuzas.
2) They were involved in the past but unfortunately it was only business. Asami was only using Fei Long to establish a new trade route through Hong Kong. He was in no way in love with Fei Long (though he does care about him to a certain extent). They broke it off due to some misunderstandings and also because Fei Long thought Asami had killed his father.
Right now, Asami only loves Akihito.
How much of romance is this? 50/50? It looks like there are yakuza involved based off some chapters and comments.
Also Fei Long and Asami were together in the past? Why did they break things off? Does Asami still love Fei Long or he loves Akihito?
Thank you. All I want to know. My OCD brain doesn’t want to read unless I know these info at the very least. I enjoy spoilers quite a lot too.