In the anime, who is not a childhood sweetheart?

Since kindergarten, I have met Yukinoshita, Hayasaka Ai, and the Kotori sisters...
[Male protagonist, multiple female protagonists, daily life]
Good news, although he was killed by the dump truck, he traveled through time.
Bad news, I traveled through time and space and became a little kid who is only five years old.
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My name is Yuan Qianye, and I’m currently studying in the last year of kindergarten.
Although my body became smaller, I was not panicked at all.
Because my system has a "God's perspective".
It is possible to observe others regardless of the laws of physics when certain conditions are met.
In addition, I can also bind with others.
I will also get a share of the improvement in their abilities as they work hard.
Knowing this, the next thing to do is simple...
(This story combines the worldviews of many popular youth anime series. Each main character in the story is described in detail. Even if you have not read the original work, you can read it as an original story.)