Starship has an allergy which makes heart shaped rashes appear all over his body when he is in love but it stops after 20 years
He couldn't feel love during the dosage to stop the appearance of these but still dated many girls but even in that period he prioritized haname, his childhood friend, more than anyone but didn't know
One day after stopping the dosage he accidentally kissed haname and discovered he had the same disease.
After a heartbreak Hiyoshi stopped believing in love and decided to never fall in love with especially with guys with tattoos disease but Kaga without persistence kept on asking and telling him he loves him and showed the hearts tat appeared every time he was with Hiyoshi
One day they suddenly stopped appearing and Hiyoshi thought he found someone he loved and thought he'd give up but he didn't
Dear Signal