I believe that Alexander is thanking KissMes as he tweeted this on the 4th anniversary of U-kiss

Translation of @alexander_0729 's tweet

In UKISS for 2 years, and alone for 2years. But in this 4 years, You guys have always been by my side. Very thankful to you all~ I love you ❤   #JustBeHappy

FACT#1 : Hashtag #JustBeHappy
Xanderettes in Singapore made a banner for Alexander "Just Be Happy" . After Xanderettes played a short video of Xanderettes thanking Xander, the video show a huge word " Xanderettes want you to............ TURN AROUND!!" And when Xander turned, all the fans there where holding up a banner with the word "Just Be Happy" I am proud to say that I have the banner with me too ^^
and Xander was so touched he almost cried !! OMO. Lol, ok I'm going off topic....

FACT#2 : He said that we have been there for him all throughout his 4 years, 2 years with U-kiss and 2 years alone. && my fanbase, @Ukissme_sg have written notes, and bought presents for him, and even went to his fan meet to support him!! We represent the minority of KissMes who still support Xander!!

FACT#3 : Xander also mentioned how he always reads his twitter replies, and tries to answer them "Indirectly". Video here 

I conclude he is thanking *Yours truly*.
OKOK, shall not be so buey hiao bai. HAHAHA.
Anyway, KissMes, do continue to show your support for Kibum, & Alexander!!

**  In which case if I offended anyone with this post of mine, I apologize. I am just a Kiss Me trying to fan -girl about Alexander, if any Xanderettes or KissMe are offended, I am very very truly really sorry. Please let my fantasy run wild over this [not so] "Private" imaginary of me and Xander. Thank you!! ^^