Middle-aged Adventurer Kein’s Good Deed

Middle-aged Adventurer Kein’s Good Deed Summary:

Kein, a middle-aged adventurer, who while in the middle of herb gathering, found a rare item 『Resurrection fruit』.
Kein thought about selling it and turned it into money, but he met a girl seeking medicine to save her companion’s life.
She looked like Altena, his childhood friend who already died, he gave it in exchange for small change.
Actually, the girl was the strongest adventurer Anastrea, people called her the sword princess. The next day, Kein suddenly got an invitation to join an S rank party, beat down the strongest and the worst monster, miraculously gain lots of money, and finally get confessed by a 20 years old saint.
Kein’s simple life will change completely because of his encounter with Anastrea.