Guardian 镇魂.  It has great bromance. it's a chinese drama

Zhao Yunlan and Shen Wei are tasked with upholding peace between deities, demons and humans, and the story will focus on their friendship that transcends past and present lifetimes.

Nirvana in Fire. Season 1 and 2. The bromance theme is very strong! (Cdrama)

Tunnel (Kdrama)

Goblin (Kdrama)

Prison Playbook (Bromance very strong theme) Kdrama

Bitter Blood (Jdrama) Father and son though. But its funny.

Flower Boy Next Door (Kdrama)

Suspicious Partner (Kdrama)