Tensei Idol to Dol-Ota no Kishi

After going through several lifetimes, Takao, a former knight, is currently living as an office worker in modern Japan. After discovering Hikaru, who is the reincarnation of the prince he served and was unable to protect until the end in their past lives, he swore to protect Hikaru in this life by being a hardcore fan.

For the sake of protecting Hikaru from a closer position, Takao decided to become his manager. But after Hikaru, who has an aloof personality this time compared to their past lives, showed him a smile directed only to him, Takao starts to feel another type of feeling budding within him!

(Source: Frontier Works, translated)