Grandpa, don't cum inside!

Even at the age of 70, Seiji's sexual desire still remains undeterred, and he becomes sexually concerned about his granddaughter Hana, whom he lives with. Seiji, a former university professor, emphasizes that sex is a wonderful act by quoting Western literature from the Sensei department, but Hana just looks down in shame. One day, after some reason, Seiji discovers the sexual impulses that Hana secretly holds, and sets a trap for Hana...