Suki na Mono wa Suki Dakara Shouganai!! −・RAIN・−

Possibly the turning point in the series. Sora and Sunao continue their life in school. All seems normal until Sora notices a child who looks very similar to him. Also, some of his schoolmates are beginning to act a little strange. Even Sora begins to notice something odd about his connection to Sunao and the relationship between their alternate personalities, Yoru and Ran. [taken from Wikipedia]