DHA sono yon!

is the fourth volume of the DHA light novel series, written by Rin Yuuki and Illustrated by Yuta Komiya. It was released under the Dengeki Bunko Imprint in January 2006.

Synopsis
Hello, this is Ai Shiratori! Finally, it seems that a date with Mitsu-kun will finally come true. Even though it's a preview of a school event, it's possible that the two of us will get closer to each other in the aquarium ...!? ...... It's embarrassing to be alone, but I'll do my best! The seven devilish girls are still trying to "corrupt" Mitsu-kun, and do something naughty with that trick ... that's not it! ow. What is it, an angel! Eh !? Mitsu-kun ran for the student council president !? But why was that Mitsu-kun ... used by someone !?

(source: Bookwalker JP - Translated)