Case Closed: The Target is Kogoro! The Detective Boys' Secret Investigation
Meitantei Conan: Hyouteki wa Kogoro! Shounen Tanteidan Maruchichousa · 名探偵コナン 標的は小五郎!!少年探偵団マル秘調査
Synopsis
Receiving a class assignment to research a profession the detective boys decide to shadow Kogoro for a day.
Source: MANGA