I don’t know how often the boys hang out actually. However, you will see Jouji or Akira run across one of the girls pretty frequently. In fact, this happened just a few days ago:
That’s Miyuu Sawai, Rina Koike, and Akira Kubodera! I believe the two ladies were independently going to see Akira in Jesus Christ Samurai Star (yes I do think I’m translating that correctly, and I want to know everything about this immediately).