Otona no Shoumei

From Shoujo Crusade:

1. Otona no Shoumei
Tsubaki always appears experienced, but actually, she has never had a boyfriend even though she's already 16, and she's a real baby. She wants to quickly increase her love experiences, and become an adult! One day, she got called out by her math teacher, Shiina-sensei, and she was told that she'll have to take supplementary lessons. All alone in the math room with her sensei after school, Tsubaki's heart beat like crazy when she saw Shiina-sensei's facial expressions that were different from usual...?

2. The Imprisoned Princess
My hard work's finally been paid off! All that studying have invited me to "ouji-sama's" house! I couldn't be more happier! But wait, why do I have to clean his house?!

3. The Prince's Mantle
Continuation of the second story. Ouji-sama and I are now a couple! Many may admire me, but he is indeed not a 'real' ouji. I still love him though...

4. The Upside Down Message
I have always loved my childhood friend. Every valentines day, I send him "chocolate messages". But, he has a harem of girls? Without thinking, I told him I like senpai, but the one I really love is him...