Bugs Bunny in Crazy Castle 4 (バックス・バニー クレイジーキャッスル4) is a platform game developed by Kemco as part of the Crazy Castle series. This is the first game in the series to feature the Bugs Bunny character in all of its versions, and the last one to be published under that license.

While cleaning out his rabbit hole, Bugs Bunny finds a map leading to a location marked "C Castle", although he does not know what the C stands for, as the letters after the initial "C" have worn away. He immediately assumes the C stands for "Carrot" and eagerly embarks on a journey to discover the castle in the center of the Taz Island, unaware that the C actually stands for "Crazy".