SideMini is a section of the game where the player can leave Souvenirs for chibi versions of the idols, after which the idols will give back a small Item in return. SideMini also refers to the chibi version of the idol themselves.
At the office, the player can leave a Souvenir. After 30 minutes, a random idol will appear, and leave a small Item (such as event stamina jelly, event AP bars, manny, or scout points). A Whistle can be used to call upon idols quickly.
Various Souvenirs can be left at the office, including:
- Event-usage: Souvenir (small), souvenir (large).
- Permanent (general): Special Souvenir.
- Permanent (unit): Special curry (Jupiter), star shaped cookie (DRAMATIC STARS), music note gummy (Altessimo), frog-shaped chocolate (Beit), soccer rice ball (W), protein bar (FRAME), higashi (Sai), donuts (HighxJoker), rice crackers (Shinsoku Ikkon), black tea and gaufre biscuits (Cafe Parade), marshmallows (Mofumofuen), space bars (S.E.M), ramen chips (THE Kogadou), mushroom snacks (F-LAGS), and old-school dorayaki (Legenders).
In the exhibition room, the player can display various things collected in the game, including:
- Event ranking trophies
- SideMini: Normal outfit, Changed outfit, and ORIGIN@L PIECES outfit
- Magazines: Covers of the magazines the player has unlocked fully
- Producer Titles
Furthermore, it's possible to buy new backgrounds for the exhibition room.