Edit: Minna, you can vote more than once. It's limited to once a day, so you can vote the next day x).
*Korean, Chinese, English, Short Comments(Saikou, Daisuki, etc) and meaningless comments are prone to be deleted.
Here's a guide on how to vote, for those who can't read kanji:
1. click on the bubble in front of Arashi 嵐
2. press the 投票 button at the bottom of the chart
3. pick your gender in 性別 section (秘密=secret, 女性=female, 男性=male)
4. pick your age group in 年齢 section
**optional: write a comment in japanese. too bad they don't accept comments written in english...
5. press the 投票する button
Guide Credits: pocco_moco @arashian.com