Are there any yaoi manga about bodyguard? I Think the story about somewhere like the boss ...

How about this one http://www.mangago.zone/read-manga/the_4th_guard/

Tight Rope is a bit like that. It's a bout a yakuza boss' son and his best friend, the yakuza son is stronger but he can't beat his best friend because...

http://www.mangago.zone/read-manga/hizamazu_ai_ni_kogareru/
http://www.mangago.zone/read-manga/pet_ja_nai/
http://www.mangago.zone/read-manga/kimi_wa_pochi_da_daigakuseihen/
http://www.mangago.zone/read-manga/tsuki_ni_hoero/
http://www.mangago.zone/read-manga/joouheika_no_oniwaban/
http://www.mangago.zone/read-manga/ijippari_love_panic/ ch3
http://www.mangago.zone/read-manga/koi_no_amai_toko/

http://www.mangago.zone/tag/bodyguard/