My favorite eel restaurant is UNAGI Futaba. This restaurant has been around for over seventy years. It is located in Susukino, Sapporo. It’s at Minami 5, Nishi 7, 3-2.
My most favorite dish is Unadon. Unadon is a bowl of steamed rice with grilled eel on top. It comes with soup and pickles. Their eels are sent directly from Kyushu and Shizuoka which are famous for production of fresh and delicious eels. The eels are carefully steamed and grilled by skilled chef.
I recommend their eel liver, too. It is a little bitter but so delicious and good with beer.
This restaurant is always crowded because it is very popular among local people.