Gaiden - Supesharu Purenzento - Amichan no Hatsukoi
Side Story - Special Present - Ami's First Love

0:11 Ami's First Love

Based off a manga side-chapter

1:07 Ami's book

English Vocabulary

1:48 Labels read

Left: Ami Mizuno, Right: Aiko Yano

2:02 Letter reads:

Miss Ami Mizuno

2:39 Fall in Love, Maidens / Climb that Waterfall, Koi

Minako seems to have confused the real saying with the legend that
koi carp that climb waterfalls turn into dragons. Based on the fact that 
"love" and "carp" both share the same sound in Japanese of "koi".

3:12 Book reads:

High School Elite

3:50 Prep school mock exams

Due to the importance for many Japanese students of getting into the
right high school, there are special schools that cater specifically to students
wanting to get good marks in their high school entrance exams.

6:15 Minako

Minako is using an expression Japanese that means "to lend a hand" but
means "willing to be helpful, even if it means taking off one's clothes".
Translated with a similar English expression here.

7:23 Sign reads:

Number One Prep School

8:04 What Ami has written says:

Mercurius

8:25 Temple-School

Private schools from the Edo Period. Seems Bonnoun is revealing her age
or perhaps this school was once one.

8:27 Bonnoun

From "bonnou" meaning "desires of the flesh" or "wordly desires".

13:50 Chalkboard reads:

Kurume Suuri --> Mercurius
Just read it backwards and... Tada!

Mercurius is: me-ru-ku-ri-u-su
To compare: su-u-ri-ku-ru-me