I thought they were in Sapporo, one of the largest cities in Japan and the largest on the island Hokkaido
Aye, it was just a little bit of sarcasm to point out the plot convenience.
It seems that it's a bit inconsistent. The contest is definitely in Sapporo but Kyoujirou is from
Otaru, until he
graduated HS. Otaru, which the web says is about a 25 minute/24 mile drive away or 30 minutes by train and has a population of just over 100,000, is supposed to be a tourist spot so from the tone of this chapter it's
possible that they went there for sightseeing.
EDIT: From the next chapter
they are indeed a train trip from their hotelso it's even more likely.
Bottom line: Don't think too hard about it...