xxxHolic Volume 04: 10/16/11
XxxHolic Volume 3 by the CLAMP uses a humorous Valentine's day story to reintroduce the shared connection with Tsubasa: Reservoir Chronicle.
In Japan girls give chocolates to boys with the hopes of receiving something in return for White day. Watanuki desperately wants chocolate from Himawari but it looks like it's Dômeki who's getting it all.
Yûko for reasons revealed in Tsubasa: Reservoir Chronicle volume 5, suggests to Watanuki that he make his own chocolate to give to Himawari. But things go awry for him and in the process, Watanuki ends up having to get back Dômeki's soul.
The second part introduces the theme of twins, a theme that will become more dominant at the series continues. There is a strong, confident twin, and a shy, unlucky twin. Watanuki wants to help the shy one overcome her troubles. In the process he learns about the way words can bind people together and how especially tight those binds can be for twins.