18 Kin no Tsukurikata

Tsugumi is a 24-year-old porn comic artist... and yet, she's never had sex with a man, and is running out of ideas for her work. She's had absolutely no inspiration, even after watching porn. She complains to art student Sena, her younger assistant. He then proceeds to put her finger in his mouth, take off his clothes, and thoroughly teach her on where and how to touch herself...?!