Responses
From what I can tell from the raws this whole manga takes place right before they get together officially. The next chapter goes back to probably... right after high school possibly college.
I think that ch 1 is current timeline so they are together... but Tenma is hiding feelings about something. They have a very strange relationship, so for all I know I'm far off.
Tenma and Yoshio they have an entire manga on them its called "Mayonaka Drastic" plus a prequel called Yoru mo Hi mo Akenai