Depends on how you define certain criteria and how lenient you're willing to be...
"A First Of Summers" meets most of the criteria, if you're willing to compare the top with a black cat as opposed to a puppy.
Another one that comes to mind is "Between Fate And Fortune" (technically it's in a university setting)
"Between the Lines" is also a good match (Juheon isn't particularly a "puppy" top. Again, deoends on how you define "puppy top")
"Bad Apple", if you're willing to consider that Rian wasn't exactly confined against his will and could get out whenever he wanted (which he did btw).
There are many such BLs... ╮(￣▽￣)╭
hotel pharus more or less fits the bill if you want to try it.
If anyone wants a challenge: is there any BL manhwa (yaoi, not shounen ai) left if I'm lf one that fulfills ALL these requirements
- they did not meet as children/in a past life
- not school setting
- no drugs (abo or otherwise)
- no confinement arc (contract is ok)
- no runaway arc
- not "puppy" top
- no close friend/relative as love rival
- they get together before last 5 chapters