Someone, please, help me to understand - Asa-chan in ch.3 said that he had sex with "innum...

Asahiko "Asa-chan"was already shown to be sleeping with Mikado "Mika", and refers to presumably selling himself to others in chap 2
http://www.mangago.zone/read-manga/asa_to_mitya/sa/sa-v1c002/1/
But presumably he thinks of Dmitry "Mitya" as being his first actual relationship, meaning he is the only one that counts.
Chap 5 & 6 have more of their story
http://www.mangago.zone/read-manga/barairo_no_kenkyuu_to_hanakurafu_kimi/

You mean in the period between when that unckle left him and him meeting Mikado? Before those girls led him to that bar? So unckle left him some money-->those money got used up--->he started selling himself--->then he met Mikado? Then why did Mikado say that he was his first man? oO
That kind of confuses me x) Maybe he was meant to say that he was his first boyfriend?
Yeah, I've read those chapters first and only then saw that there is an actual manga about Asa and Mitya)

Having re-read it, I think I made a mistake. The timeline appears
- Asahiko's parents die
- Asahiko goes to live with an older family member, he gets upset over his feelings for him and starts to wander about the streets. Using up whatever money he had with him.
- He gets picked up by Mika's friends
- Mika and him sleep together, and Mika appears violent
- Asahiko is now a drifter and rarely goes to secondary school. On the rare day he does he goes to the roof and sees Dimitri (who assumes he is going to jump). Asahiko, plainly asks him if gay (too) and so begins their relationship.
- They are then shown 6 years later, living together.
- In the next volume Mika is shown getting married to the dark long haired man that he has too known since secondary, and was also shown amid Mika's group of friends when Asahiko was with them.
Whether Asahiko slept with more people other than Mika, before he met Mitya wasn't shown. I made an error saying he sold himself when he was getting picked up by Mika's friends. I guess Asa-chan regardless of his previous experiences, considers Dimitri to be his "first man" as it's been the first relationship where love was involved, and it has been reciprocated.

Yeah, that is why I was (and still AM) confused - because it was never shown that he slept with anyone else except Mika and Mitya. No flashbacks, no memories, nobody ever mentioned it - only that time in the bathroom (when Mitya cut Asa-chan's hair) there was that phrase about "innumerable" people" ┑(￣Д ￣)┍ And that's it.
Oh, but I've also never seen that Asa-chan said that Mitya is his "first" anything (only that he is finally not alone and in love), that phrase about the "first man" belongs to Mika - he said it in the end of ch.5.
Mitya: "Who're you?"
Mika: "In terms of order... Guess I'd be the guy before you? Seems like I'm Asahiko's first man."
Jesus xDD I'm stuck. Maybe in the second volume Mika would say smth that will clear it all out (I wish I knew Japanese), but at the same time I doubt it x) There are some moments in this manga that are kind of "lost in translation", I guess? Or maybe it's just author's own narrative style oO