Yaku (薬) was a Magic-User and one of two thugs that tried to capture Noi and Shin and force them to become their partners along with his companion Baku. His specialty was tranquilizers and that might be his type of magic.
A surgeon motif attire armed with a gigantic vaccine.
Ruthless, cunning and prepared, Yaku set a trap for Shin knowing his target movements the moment Shin knew about Yaku was alive, incapacitating his target from far away.
He was seemly killed almost 9 years ago when he and Baku assaulted the Flower smoke in a failed attempt to kidnap the soon to be cleaners as partners. Shin apparently killed Yaku without effort back then and Noi crushed Baku's head with a huge boulder, believing that was the end of them.
Along with Baku, they came back for the last Blue Night Festival to ensure their membership as part of the En Family by kidnapping and forcing once again Shin and Noi to be partners with them.
Yaku successfully drugged and kidnapped Shin and flew in a Magic Broom to meet Baku, who also secured his target, sadly for them they stumbled across Kaiman and the workers of Restaurant Tanba. The lizard head, along with Fukuyama, dispatched the duo unintentionally saving the cleaners in the process, Kaiman killed Baku and Fukuyama morphed Yaku into a meat pie.
Ebisu found and ate Yaku's morphed body believing it was just a yummy pie on the ground, killing him for good.
- His pie form made Ebisu have a strong stomachache.
- Its quite possible his magic was related to some sort of medical procedure, explaining why he would need a partner with the power of cut people without the danger of killing them.