"Progressive Rejuvenation Syndrome." This is an extremely rare disease
causing the inflicted person to gradually become younger. The main
character of this story, Munenori Agawa, is the only person that could
save Rena Amami from this odd disease. Agawa's saliva is the only thing
that can halt the disease from making Rena younger, so they must kiss
everyday in order for her to survive. This causes an immense amount of
conflict and drama between Agawa and his new girlfriend, Sayako Asou.
This triangle relationship story tests the capabilities and limitations
of human love.