So… I just found these mp3: Wasurenaide (a capella version) and Bolero (piano ver).
Wasurenaide (a capella version) is an official track, as hidden track (okay, so it’s not a hidden track, lol thanks to ICD for telling us so) is just a ripped mp3 taken from Wasurenaide song in Bolero/Kiss The Baby Sky/Wasurenaide single. So it’s confirmed that the hidden track is only どうして君を好きになってしまったんだろう? -Royal Mirrorball Mix-
While Bolero (piano ver) is another great score from tvxqpiano@LJ.
The a capella is not….. really a capella for me ^^:: I think it’s more like the boys were rehearsing to Wasurenaide before recording. I would prefer their fabulous Ha Ha Ha a capella singing other than this one, but you can listen to each of their vocals better so it’s still worth to listen to ^^
Just check them out <33
File Name: TohoShinki – Wasurenaide (Acapella Ver.) [sharingyoochun]
Size: 10.7 MB
Duration: 4:36
Link: Mediafire
credit: qoojunkie@z-degrees + sharingyoochun@wordpress
File Name: Bolero(tvxqpiano@LJ) [sharingyoochun].mp3
Size: 5.6MB
Duration: 6:07
Link: Mediafire
credit: tvxqpiano@lj
Uploaded
www.sharingyoochun.exteen.com/20090131/mp3-wasurenaide-a-capella-ver-bolero-piano-ver
sharingyoochun
wasur3naid3
piao
ayu333
already listen to the wasurenaide acapella version…
just like you, i like their acapella version of ha ha ha better…
but its still ok coz’ the song was written by jae…
By: mimie19 on January 31, 2009
at 10:24 pm
thanks for sharing the acapella version of wasurenaide..
this is my most favourite song in the single..
it would be great if the song is in full version..
By: junsheng on January 31, 2009
at 11:26 pm
thanks for the upload.
i seem to hv missed the hahaha acapella, going back to grab it. thanks again!
By: alice on February 1, 2009
at 3:33 am
thanks.. but i dont understand… hidden tracks?? wth, ive bought the cd & its not there?? heeeelp ==”"
By: nina on February 1, 2009
at 7:58 am
I thought I’d point out that the acapella track above isn’t an official track. It’s simply a track done by a person (probably a fan) who ripped the vocals out. It’s quite obvious/an easy thing to tell especially because of the beginning and also they sound like they are singing in a tin ^^; I’m more than 100% sure about this since i’m a mixer myself. you can easily do that with all the other tracks so yearh… wherever you got the information/source from it wasn’t true.
By: ICD on February 1, 2009
at 8:18 am
Shinta@ICD:
ahhh really???
I’ll edit the desc then. thanks 4 the info ^^
By: sharingyoochun on February 1, 2009
at 8:24 am
thanks! ^^
By: kpop-th on February 1, 2009
at 8:33 am
thx for sharing!!!
By: norah on February 1, 2009
at 3:05 pm
Thank you
By: pompurin on February 25, 2009
at 11:30 pm
Thanks!
Is it just me or does it end weirdly (Wasurenaide)? IDK maybe there was a downloading error, but mine sorta cuts off at the end :\
By: yanna on March 24, 2009
at 4:55 am
Honey, I think your Wasurenaide is edited. They do it to a lot of songs, removing the arrangement to leave the vocals and all.
I have the single, and it isn’t in it. 
By: Rai on March 26, 2009
at 11:35 am
legra@rai:
yup, it’s not actually an acapella version… it’s just the voice with the bgm being edited out… but since it’s only the voice, haha, people tend to call it acapella ^_^
By: sharingyoochun on March 27, 2009
at 1:33 am
thank
By: 김보나 (@bow039) on October 29, 2011
at 2:51 pm