Born in Singapore, By2 consists of a pair of twins who are now based in Taiwan. Younger of the 2, Yumi wrote on her Weibo page:

@by2girl新浪个人认证 ：我們非常欣賞的全方位Big Bang 已經離開臺灣啊！嗚嗚..謝謝@司徒建銘 來不及看但拿到你們親筆簽名已經足夠了 愛不釋手惹 ！！開薰～Wow fantastic baby!!Yumi

Translation: The Big Bang that we admire already left Taiwan! Huhu.. thank you @司徒建銘, even though we didn't get a chance to see but we're contented to be able to get your (referring to BB) autographs we love it !! Happy~Wow fantastic baby!! Yumi.

Source: http://www.weibo.com/u/1359703040