>>280529506my guess is he could manipulate sadness as well as joy, he just chose to do the former in kagami country
if Ichi attacks with bakugami, most probable is absorbing sadness from world hater (and overload bakugami in the process), but I think he might also be able to inject joy emotion into world hater (or awake the suppressed feeling that's already there, that time when world hater grinned at ichi)
either way, Bakugami is no doubt vital majik to attack world hater with, that's why the prophecy sent ichi to hunt it in the first place