Shini Yasui Kōshaku Reijō to Shichi-nin no Kikōshi - Chapter 42: Burial Chamber of Angels (part eight)

There are 5 books on the 6 sworn brothers in a serial called streamer (流光系列). ‘They are rich, handsome and powerful. These book are on various types of love as well as on the bond and mateship between the brothers. Book on youngest 6th brother.

Chen Yu Bai (3rd brother) & An Xiao Yi – Chen Yu Bai is a sharp, domineering & cool man whereas An Xiao Yi is a foolish, childish & innocent girl. He is her boss & she is his secretary. He bullies her yet at the same time will not hestitate to protect & shelter her. Thus, she can always rely on him. Their relationship is a funny one on how opposite attracts.

Li Wei Ran (5th brother) & Qin Sang – Li Wei Ran and his cousin Qin Song fell in long with Sang Sang who is An Xiao Yi’s best friend. Sang Sang sees Li Wei Ran as a good man. He is polite, patient and passionate whereas she is independent, intelligent and interesting. They are a perfect pair but she is afraid to love so he has to work hard to convince her he is worthy of her love..

Short sequel on their children.

On earth, Felix is just a normal guy, a bit of a loner but otherwise normal. In the multiverse, under the rule of The System, he's a caster. Fascinated by magic and hungry to learn, grow and discover, this series follows Felix on his adventures through the integration and beyond.

Xiao Ze, who was dedicated to the people and vowed to become a generation of Ming Jun, accidentally fell on a little lady.
The little lady was born beautiful and lovable.
So Xiao Ze accepted his life and got the name of fear.

ps:
①The male protagonist has no concubine, and he is dedicated to serving the country.

- Description from novelbuddy

The poor aristocrat Viola suddenly received an unexpected marriage proposal from the prestigious noble household of Duke Physalis. An average noble daughter and the handsome duke. She had been confused, thinking that nothing made sense, but the duke had his own personal reasons. A political marriage with ulterior motives, both having their own circumstances. Will this path lead to happiness or sorrow?