Considering he was a Japanese college student, I'm thinking it's most likely his pets are family pets. Apartments there are very small and many don't accept bigger dogs. The pool for student apartments is even smaller and I doubt most of them would allow two pets. Those that do are most likely not affordable for a student. Based on this, I would wager his pets probably live in the suburbs at his family home.

Maybe it’s because I live in the US of A but the idea that my pets might be trapped in an apartment all by their lonesome for who knows how long is dreadful. What do you mean you’ll live there. Are they fed? do they have water? will someone notice in time that they’re alone? If they do, will it be animal control or someone else who takes care of them? Will they be kind people? How much trauma will they suffer? I literally could not swallow all that and accept it. Like I know it’s BL and sweet but I got my babies to go back home to… so come hell or high water I’m blackmailing and using all my magical capacity to wreck havoc to force the powers that be to get me home or bring them here