Misshitsu no Hisoka na Hoshi

Another detective agency just opened in the same building as Ukai's. The new detective is his old high school classmate, who insists on helping Ukai despite his protest. His classmate has always been standoff-ish back in school, so is there an ulterior motive why he's showing up now? --------- A detective has set up a new agency right next to Ukai's own and it turns out to be none other than his old high school classmate, Kondou, aka Chikamichi. Easily eluding all of Ukai's protests, Chikamichi bit by bit helps with Ukai's commissions until he starts to nonchalantly begins to hang out with Ukai. Back in high school, Chikamichi had placed a bit of distance between Ukai and himself, which shocked Ukai a bit. What could be the reason for Chikamichi's reappearance in Ukai's life?