Ginpaku no Paladin - Seikishi

Kogane Kokoro wanted to reach out to someone in need in the train but was unable to do so. Then a mysterious old man appeared and took down those goons with his swift movements. Impressed by the heroic appearance, Kokoro decided to become stronger. He became the disciple of the old man and started learning fencing...! A man becomes stronger due to the desire to protect! An action fantasy story unfolds.[Source: MangaUpdates]