Okay, if I'm interpreting this correctly (without being able to read any of it), from right to left, these are Harima-and-Yakumo's daughter, Harima-and-Eri's daughter, and Karen's daughter? And the two half-sisters were raised as sisters, Harima being with both girls (in some extralegal manner). The boy in the second chapter seems to be Mikoto and Hanai's son, and the fourth girl is -- well, I'd guess Akira's daughter, just based on the gunplay, but it doesn't seem spelled out.

Damn, I'm curious on this one.