Secret Of The Sakura

This is a KHR fanfiction with a slight mixing from Honkai Impact 3 (by the way, i don't know what to put on the title yet lol)

Sakuno Hoshizora is a Tsunayoshi Sawada's step sister, who was taken in by Sawada Nana at the age of 10.
To repay Nana's kindness, Sakuno swore to protect Tsuna and be by his side no matter what, so does Tsuna.
When a baby named Reborn, who called himself the world's greatest Hitman, showed up and suddenly said that Tsuna is going to be the next Vongola heir, Tsuna was afraid. But Sakuno reassured him that everything will be alright, and she will still stay by his side.
But everyone has their secrets, and so do Sakuno... Or does she?

find out the journey of Sakuno Hoshizora in this book~

Also, this may or may not be a Hibari x OC