There was a manga I remembered reading but I can't remember the title. I haven't seen it in about 5 or 6 years ago.

EDIt AGAIn:
I think it was a shonen manga. It was about martial arts class full of elementary school kids, who are paired in two partners. A lone boy was seeking and trying to find a partner with another classmate in the class. So he set up a prank in order to separate the people who are not scared from the people who are scared. The purpose was to seek a partner from the people who aren't scared by the prank. The female teacher ordered all students to go into a cave to pass a test. A boy had his leg/foot injured. The MC helped him. Then he learns the injured boy has a partner who is a an aloof and cold boy. A lot of students, including the injured boy that the male protagonist is helping are killed when the female teacher detonates the explosives that caused a cave-in collapse but others escaped.

In the next event, the students are ordered to take another test which involves poison and antidote that works only when two pills are consumed together. That was the last chapter I had remembered reading.

By the way, I meant to say shonen, not shone in the title

Interesting story, tag me if you find it

I apologize for one error in my thread post. The school was actually elementary, not kindergarten which I mistakenly mentioned in the description I wrote in the thread post. The kids, as I recall, look clearly at least 11 or 12 years old. So maybe they are 5th or 6th graders, I think.

Is it 7 Seeds?

Rokkon Shojo
TeppenMezashiteTondeAruYo
Let justice be done, though the heavens fall

Quote from Potchan

Is it 7 Seeds?

No, I am afraid it is not the title I was looking for but thank you,