This is a spoiler-free walkthrough for CORPSE-PARTY-0.
- After the long cutscene, Shiho Hasegawa will join your party and exit the classroom.
- Another cutscene will play out. Afterward, Masayuki Hayashi and Hideki Tachibana will join your party.
- Investigate the gap leading to the stairway.
- Go south down the path next to the stairway and then turn east.
- A cutscene will play out. Afterward, investigate the loose board to pick it up (it will look different from the rest of the floor).
- Go back to the gap and use the loose boards. Then go up the stairs.
- On the 2F, go to the first opened door to the right.
- A cutscene will play out. Then there will be an option to choose, choose any as they don't affect the outcome. After the cutscene plays out, leave the classroom.
- Another cutscene will play out.
Congratulations, you have beaten CORPSE-PARTY-0!