hezaa- What I learned to do, if I'm feeling lonely and missing my friends is just send them a message saying that I love or care about them or "hey, I'm grouchy, tell me something that will make me laugh." That way, they know they're important to me and I starts a really good conversation between us.
I usually don't lead with a word vomit of everything I'm feeling because I just don't know what kind of emotional space they're in.

Remember, your friends aren't your therapist. If you can't see your real therapist and really, really need to get all of that icky stuff out, call Befrienders International. This is their Japanese number: Hotline: +81 (0) 3 5286 9090