Time Traveler's Method

Translated from the manual

All players have spent six depressing years in junior high and high school. The only somewhat colourful memories from those years are the memories together with their childhood friend and the class' top student, Shizuka Miyamoto.

On the graduation day, Shizuka left with the words "I'd liked to have really fallen in love with someone", and a couple of months later, the players are devastated as they hear she has married some guy her parents introduced.

Soon thereafter, the players see an advert recruiting people wanting to participate in a "time-space jump experiment. Only for people with strong minds."

The players participate in the experiment, and use the time machine to try to improve their past. The time machine is powered by strength of mind. The unhappier past, the stronger mind, so at the start, players are able to go back all six years. But as they change the past and get happier, their mind weakens.

Who of the players will be able to catch the heart of Shizuka Miyamoto?