LOONA TV #255 is the two-hundred-fifty-fifth episode of LOONA TV.
The first day of filming for the "Heart Attack" music video starts with four members in the dressing room. The girls try to convince the editor to do a (literal) jump cut between their casual outfits and MV outfits. Once dressed, Chuu leads her members in doing a particular move from "Heart Attack"'s choreography.
- This is the first episode in which Chuu is called "Chuu".