I would like a stronger hint lol. I wish there was a guide for this game lol
Okay. For Yoshiki's Side, you just need to progress through the game until after they return from the real world, then you should encounter Naho. If both Yoshiki and Ayumi are alive, she'll give them a Power Stone, which will allow the two to take the shoes from the Science Lab and survive. After that, Yoshiki needs to use the gas burner against the anatomical model, same as in the routes where he dies. The Power Stone will repel the model and allow both characters to survive.
You can get the blessed shoes at any time once the Science Lab opens, but for everyone to survive, you need to get the Power Stone first.