Lancer.

About Lancer

Undertale and Deltarune are fantasy role-playing video games developed by Toby Fox. They take place in different fictional universes, but feature many of the same characters. Undertale is set in a world where monsters once coexisted with humans on the planet's surface, but, after an ancient war, were trapped in the Underground and forgotten. The game follows Frisk, a human child who falls into the Underground via an opening adjacent to Mount Ebott, and seeks to escape.