Naoi Rei, unfortunately, covered this song in Korean.
The version sung by 10cm is no more than a cover of the original japanese version , released in 2010.
10cm's cover of the above Japanese song has defeated even the mighty IU, who had terrorized KPop for 15 long years.
So , since nobody in KPop could defeat her, it was perhaps fitting that a Japanese song crushed her in the end, like Lee Sinsun being put down by a Japanese sniper, whose name is lost to history, in the final stage of the Japanese invasion of Korea in 1592-1598.
Rei blew her chance, but there are other members of KPop groupis hailing from Japan.
I think they should all do Japanese covers of Kimi ni todoke, to celebrate the reconquest of Korean Pop by Japan and also to denigrate IU, who finally met her match after 15 years of terrorizing KPop by a Japanese song.