Dareyanen

One day, Ikuto wakes up to find Kentaro, a senior in high school, standing in front of him, calling his name and smiling warmly. The strange thing is, Ikuto has no idea who Kentaro is. Confused, Ikuto bluntly asks, "Who the hell are ya?" However, no one around him seems to find anything odd, as if Kentaro's presence is perfectly normal. Ikuto is left feeling isolated in his confusion. To make matters more unsettling, Kentaro leans in closer and asks, "Did ya really forget me?"

(Source: Mag Garden, translated)

Note: Chapter count includes an extra.