The high school actually takes part in that graduation video event? So I presume it's one of those high schools specifically for students in the entertainment industry (like Hinode, for example)?
The piano clip above has been removed, so here is Erika playing from Sergey Prokofiev's Piano Sonata No. 2:乃木坂46 生田絵梨花 プロコフィエフ ピアノソナタ第2番 4楽章 {With thanks to domdomgongon}
Ikuta Erika to star Musical "Princess Knight"August 24, 2015 Nogizaka46 member Ikuta Erika (生田絵梨花) will be the leading actress of manga magazine "nakayosi" 60th anniversary musical "Prinicess Knight", "Princess Knight" is adapted from classic manga "Ribon no Kishi" by Osamu Tezuka.Nogizaka46 member Ikuta Erika (生田絵梨花) will cast the leading character "Sapphire" and another Nogizaka46 member Sakurai Reika (桜井玲香) will cast the character "Hecate".Ribon no Kishi is a Japanese manga written and illustrated by Osamu Tezuka. This manga follows the adventures of Princess Sapphire, a girl who pretends to be a male prince to prevent the criminal Duke Duralumin from inheriting the throne of the reign of Silverland. It was serialized in Kodansha's nakayoshi from 1963 to 1966.The musical is scheduled on Akasaka ACT Theater, Tokyo from 12 to 17 November 2015, and on Theater BRAVA!, Osaka from 3 to 6 December 2015.
Looks like a couple of members are taking part in another production of "Ribbon no Kishi" (a story that Platinum Era MM fans are familiar with ).QuoteIkuta Erika to star Musical "Princess Knight"~SNIP~ - http://akb48-daily.blogspot.ca/2015/08/ikuta-erika-to-star-musical-princess.html
Ikuta Erika to star Musical "Princess Knight"~SNIP~