From Wiktionary, the free dictionary
From でれでれ (deredere) and 期 (ki).
デレ期 • (dere-ki)
- デレ期: (slang, fiction) lovey-dovey period of tsundere
- Coordinate term: ツン期 (tsun-ki)
- デレ期, dr期: (idol fandom) period of infatuation with an idol
- Coordinate term: 冷め期 (same-ki)