From Naono Holics:

After the death of his best friend from childhood, Gunji, the Buddhist monk Isana loses the ability to cry, as well as his chance to ever tell Gunji how he truly felt about him.

His grief and anger end up focusing on Tanabe, a junior detective who used to be Gunji's favorite at work. Tanabe, with his optimistic and outgoing personality, is the complete opposite of Isana, and seems to handle the loss much better than Isana himself.

Abhorrent, Isana can't help thinking.

That's why it's almost as great of a shock to Isana as it is to Tanabe when Isana, a monk, throws at Tanabe the words:

"Will you comfort me in Gunji's place, then?"