Saitei Rank no Boukensha, Yuusha Shoujo wo Sodateru Orette is a Manga/Manhwa/Manhua in (English/Raw) language, ACTION series, english chapters have been translated and you can read them here. You are reading chapters on ManhwaZ fastest updating comic site. The Summary is
The old man who matches the number is actually a legendary adventurer! The strongest training fantasy from becoming a novelist!!