Manga Good Deeds of Kane of Old Guy

Kane was a typical middle-aged adventurer who went out collecting herbs for potions. However, suddenly he will find the rarest item that will help him get rich. As a result, enjoying a job, he meets a girl who asks for help in finding an extremely rare herb in order to save his girlfriend. And this girl was incredibly similar to his childhood friend. He does not yet know that this girl is the strongest adventurer who received the title of the legendary princess of the sword. Soon the guy for his kindness receives an invitation to the strongest guild, together with which they go to kill the most dangerous monster! Kane's whole life will change dramatically because of this girl. What does the future hold for him?