Was Natsuki's first love, Atri? His beautiful childhood memories are gradually being overwritten. Despite his unwillingness to admit it was her the facts around him are lining up to force him to, but he continues to deny it. 
but is there actually a way to prove that
something has a heart or emotions...?
لكن هل هناك وسيلة حقّاً للإثبات
بأنّ شيئاً يمتلك قلباً أو عواطف؟
Comment démontrer qu’elle éprouve
bel et bien des sentiments ?
ma non c'è un modo preciso
Но как стопроцентно доказать,
что у неё есть чувства?