Do you know the name of the Doujinshi?

Good evening.
I was recently looking for some good Doujinshis I'd read in the past 5 years and I'd found most of them again but a special one is still missing.
I am only remembering pieces so here I go:
- the main protagonist is proablly on his way home and passing through a street with many shops and stuff
- he noticed a young woman which is standing infront of a gym and calling him over and I guess she is asking for his help or something (It could be that she has a well trained body)
- inside they start training, doing execise and stuff
- days are passing by and his body is looking better then before
- btw they didn't do it with each other until now
- at the end the young women shows him a outdoor bath proablly at the rear of the building
- and finally they tell each other that they were enduring their lust the whole time and they engadge each other

the end

Well, I guess you could call that Vanilla?
Mhhh
Please help me to find it!
Oh and btw sorry for my bad english.

Greetings from Germany ;)

Shape Up by Pyon-kti

And since you have the book you have access.

Thank you very much.