1-2. man who eats roses and scientist who research on shining roses.
3. basketball team. kouhai teases senpai whho is a virgin.
4. guy just dumped by wife to host guy. host guy is actually gay and comes onto seme.
5-6. seme used to be a delinquint and got hooked onto a gay guy. they are couple of 6 years and live together for 3 years.
Barairo no Kenkyuu to Hanakurafu Kimi