Whew. Finished another playthough up to the pre-DLC credits roll with 6h51.
Correct. The earliest the game can end is Fri. day 103 (if you completed the Grand Adventure on Sun. day 98 or before), then credits rolls and it pops you back in post-game mode with the hot springs (1.1) and DLC story (2.0) stuff.
A lot of CGs (the entire Page 2 of the Story section) are in the hot springs and DLCs.
There is a bad end CG (imouto pregnancy), which can be missed if you didn't trigger the relevant bad end (obviously). You can no longer get her pregnant after completing the GA.
Most other CGs are RNG and not
technically missable, but not exactly easy to obtain:
- The wet dreams with your imouto or guild members. A random one can be seen by sleeping with Lust 120 (and a non-sexually frustrated imouto). DLC brings new ones, which can be seen before the ending (had new Kana, Yui, Yukari wet dreams before clearing)
- Although it does not show up in the Memory screen, said sexually frustrated imouto will assault you in your sleep (there are multiple variations of this CG, selected randomly),
- Guild member CGs happen randomly, including shower scenes (random at end of day) and stories (which will raise the power and affection level and end in a sunset CG). Including Yukari.