How to Help a Japanese Sensei Save Face and Not Drink

My friend is going back to Japan for two weeks to visit his favorite dojo and sensei. He's going with two friends (all are from the US). They do this trip almost every year. Usually, they go out drinking with the sensei and get really, really drunk. The sensei had a medical issue year and is not supposed to drink. This information came from his family (not the sensei) to my friend. His two friends still want to drink and have a good time, etc., but my friend wants to find a way to help the sensei stay healthy and also save face not drinking.

Should he try to do other things in the evening with the sensei that don't involve drinking? Should he perhaps lie and say, oh, I'm taking medication and cannot drink, will you join me? Or is there something he can do to help out without making a problem? Any ideas?

Weird question, I know! Thank you for any suggestions.