Isshuu is the recipient of Jakanja Love Arrow Monster
With Nanami as his first love, but ... another rival come in
Isshuu made his move
And with a cow, "..because you like cute animal"
and beautiful Nanami just.... "Huuuuh ???"
There is one more love/ring/proposal episode theme in Episode 13 Moustache and Engagement Ring (ヒゲと婚約指輪). A well written episode, about a missing proposal ring, ending scene:
HAPPY VALENTINE's DAY