If you zoom into her graduation certificate, you can see that the degree is in 環境情報学
From Keio's official site, in English this degree in translated to Bachelor of Arts in Environmental Information [B.A.(Environmental Information)]* (http://www.sfc.keio....lumni/faq.html)
If you wanna know exactly what she was studying (is not Computer Science) here's the English site http://www.sfc.keio.ac.jp/en/