I thought it was Kamakura Jogakuin (Girl’s School)
It has a sailor’s suit with lines, a pocket on the chest, and a beret.
It is on Wiki as such, and it looks like it hasn’t changed since the olden days:
Winter uniform – dark blue sailor suit. There are three white lines on the collar and cuffs.
Summer uniform (long-sleeved) – Sailor suit with white background. Dark blue collar and sleeves with three white lines.
Summer uniform (short-sleeved) – Sailor uniform based on white. Of the dark blue collar and sleeves, only the collar has three white lines.
Ribbons – High school students tie black ribbons and junior high students tie navy blue ribbons (made of silk) for both winter and summer uniforms. The knot is tied with both wings wide open above the knot, commonly called the “Kamajyo Knot”.
School badge – The school badge is made of sterling silver with the image of a white chrysanthemum on the chest.
It is a classic and simple sailor uniform that has never been redesigned since it was established in 1935 (before that, it was a kimono uniform).
Until the early 1990s, there was also a beret and a designated bag (the beret still exists today, but wearing it is optional).
しょうこさんから下記のメールを頂きました：
鎌倉女学院じゃないかと思いました。
特徴は、線の入ったセーラー服、胸のポケット、ベレー帽。
Wikiにこう書いてあり、昔から変化してないみたいです。
冬服 ‐ 紺地のセーラー服。襟と袖口に3本の白線がある。
夏服（長袖） ‐ 白を基調としたセーラー服。紺地の襟と袖に3本の白線がある。
夏服（半袖） ‐ 白を基調としたセーラー服。紺地の襟と袖のうち、襟のみに3本の白線がある。
リボン ‐ 冬服・夏服を問わず、高校生は黒、中学生は紺のリボン（絹製）を結ぶ。結び目より上の両翼部分を大きく広げた結び方が特徴で、通称「鎌女結び」と呼ばれている。
校章 ‐ 白菊を象った純銀製の校章を胸に付ける。
1935年に制定して以来、一度もデザインを変更することなく、古典的でシンプルなセーラー服である（それまでは和服の制服であった）。
1990年代初頭までは、ベレー帽と指定カバンの設定もあった（現在もベレー帽は存在するが、着用は任意）。
We received the following email from Shoko:
I thought it was Kamakura Jogakuin (Girl’s School)
It has a sailor’s suit with lines, a pocket on the chest, and a beret.
It is on Wiki as such, and it looks like it hasn’t changed since the olden days:
Winter uniform – dark blue sailor suit. There are three white lines on the collar and cuffs.
Summer uniform (long-sleeved) – Sailor suit with white background. Dark blue collar and sleeves with three white lines.
Summer uniform (short-sleeved) – Sailor uniform based on white. Of the dark blue collar and sleeves, only the collar has three white lines.
Ribbons – High school students tie black ribbons and junior high students tie navy blue ribbons (made of silk) for both winter and summer uniforms. The knot is tied with both wings wide open above the knot, commonly called the “Kamajyo Knot”.
School badge – The school badge is made of sterling silver with the image of a white chrysanthemum on the chest.
It is a classic and simple sailor uniform that has never been redesigned since it was established in 1935 (before that, it was a kimono uniform).
Until the early 1990s, there was also a beret and a designated bag (the beret still exists today, but wearing it is optional).