姉と幼なじみは中がイイ！ ～「ニンベン」ついてないし…～

Protagonist is excited about the start of their summer vacation. However, things take a turn when his father, a geologist in South America, sends him a mineral sample containing an ancient pathogen. This leads to their family being at the forefront of a "love pandemic." The infection targets those who have unrequited love, causing them to experience mild infatuation symptoms. The treatment involves releasing one's desires and not holding back on their feelings. The protagonist's summer vacation becomes an exciting and somewhat risqué adventure, involving his two sisters and childhood friend from next door. Will they be able stop the pandemic in time to save humanity?