Heartseed is still playing games with Taichi, Iori, Himeko, Yoshifumi, and Yui. They've already swapped bodies, changed ages randomly, and explored their innermost desires. But now, a new virus is spreading among them. Called emotion sickness, it causes intense feelings to jump from one person to another without warning. This condition can be especially distressing for those with phobias or repressed emotions, and in extreme cases, it can be fatal. What is Heartseed's motive for making the characters divulge their personal secrets against their will, and what other surprises does he have in store?