Case Closed: Season 1, Episode 496
1 - 496: Clash of Red and Black! (Invasion)
The nurse tells Conan that she just remembered Eisuke had surgery for leukemia when he was young, raising the possibility Rena may in fact be his sister.
The nurse tells Conan that she just remembered Eisuke had surgery for leukemia when he was young, raising the possibility Rena may in fact be his sister.