i found a guide on a japanese website on how to view all scenes:
一本道のゲームです。
エレベーターで表3裏3回選択肢を選び左のメーターを最後まで上げれば次に移ります。
会議室でも同様のことを行えば全シーン閲覧可能です。
"It is a one-step game.
In the elevator, you have to choose 3 times from the front, 3 times from the back, and raise the left meter to the end to move on to the next.
You can view all the scenes in the meeting room by doing the same thing."
I think it means view all position from front (all have to reach climax), then all behind (all climax end too) and then the same in the meeting room.