LOOKING FOR A YAOI THAT I LOST!!!!!!!!!!

A scientist is looking for a place where to do his research
He finds a place, but a kid (he is 12 or 13) plays there
Then the scientist finds out that the place belongs to the kid bc he is very rich
The kid then tells him that he will give him the place in exchange of the scientist playing with him and so.
Since the boy doesnt have any friends at all
One day while the boy is playing in the new laboratory, he enters a machine where he grows into a man
The scientist is attracted to him, and they have sex, after that the kid returns to his normal size, but the boy loves to have sex with the scientist so he keeps entering the machine, and have sex with the scientist.
The scientist afraid that something bad could happen to the boy bc of the machine, promess him to be his when he turns 18.
They stop having sex and wait until the boy is 18.

HELP, I love this manga

Second story of Sensei to Himitsu.

thank you very much!!!!!
Arigato!!!!!