Volume 2 had been released on May 13th:
Drug & Drop Volume 2 TPB
After completing Watanuki’s request, Rikuo disappears, with his own ever-mysterious purposes. Fraught with worry over Rikuo, and bearing the new burden of “carrying memories” all by himself, Kazahaya makes a rendezvous at an unknown house—whose signpost has his family name! From behind the wisteria tree appears something even more unexpected . . . a tiny angel named Kohaku.
* Crosses over with the CLAMP universe!
*A new ongoing series.