Ring Ring: Eiyuu Kishi to Isekai no Otome
リングリング 英雄騎士と異世界の乙女
A university student named Shiori once cared for a knight who was unexpectedly brought to Japan. After the knight returned to his own world, Shiori found herself transported there instead. Stranded and alone, she set out to find the knight, who in this new world has become a hero.