|Occupation||Cram School Teacher|
|Family and Relatives||Kyomi Kasannoin (sister)|
Kyouichi Kasannoin ( 花山院 恭一 ) is the mentioned boyfriend of Nanami Kanroji. He is also has a more prominent role in the game Cross Days. There Yuuki Ashikaga looks up to Kyouichi Kasannoin as his mentor and senpai. Kyouichi enjoys playing eroges, works part-time as a tutor and looks to Yuuki as his kōhai.
- He's the fourth person to be shown killed by Kotonoha, after Sekai (in School Days), "Yuuki Ashikaga" (in Cross Days) and Makoto (in Shiny Days).
- Kyouichi's front as cram school teacher for his pedophile activities and his infidelity is similar to Tomaru Sawagoe's actions through out the Radish Trilogy.