E is for Etching
Etching: the act, art, or process of making designs or pictures by the corrosive action of an acid. (- Naru is an acid).
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Some people leave scars on the hearts of people. Some leave bruises. People could leave minor scratches or stains, or break the heart. Some hearts, which were as fragile as glass, could shatter. Others, made of brick, took the pain and gashes without crying.
Mai thought her heart had shattered after Naru rejected her. She was wrong. Although her heart was not made of stone - no gashes marred the surface.
Naru hadn't left that. He had left an etching on her heart. An etching that could never be removed or faded, and would be imprinted on her heart, forever.