Having undergone only two months of training, Ryeowook's late addition was rumored to be a replacement of a previous SM trainee that was supposed to debut as a member of Super Junior 05 as the first generation of Super Junior.
Setelah mengalami hanya dua bulan pelatihan, akhir Selain Ryeowook itu dikabarkan menjadi pengganti dari SM trainee sebelumnya yang seharusnya untuk debut sebagai anggota Super Junior 05, generasi pertama dari Super Junior.