I'm surprised the translator didn't catch this, but:
Inui Ken
Sarutahiko Mei
are also a reference to dog (inu) and monkey (saru).
The Japanese have a proverb: 犬猿の仲 (ken'en no naka), literally "a dog and monkey relationship", and means "bad relationship", like cat and dog.
Considering "Dry Sage" looks a bit like a dog (his hair is shaped like animal ears) and the two also seem to have a bad relationship, I'm fairly certain that's how the author intended those two to be interpreted.