Guardian Fanfiction: Do You Still Remember?

Near Longcheng University, there is an elegantly appointed bookstore run by a pair of brothers. One is cool and aloof, while the other is warm and hospitable, like ice and fire in perfect balance.

Rumor has it that there are two passages between Planet Earth and Planet Sea. One is overseen by the Black-Robed Envoy and the Regent, while the other is guarded by a pair of twin engravers. It is said that when they appear, one wears a silver mask with blue patterns and the other a silver mask with vermilion patterns. Not even the Black-Robed Envoy has seen their true faces. The one wearing the blue-patterned mask is cold and strict, while the one in the vermilion-patterned mask seems warm on the outside but is cold within. Anyone they catch trying to cross the boundary is killed without mercy. Even the Black-Robed Envoy's pleas are useless.