This group was established in honor of the character from the anime "Re: Zero" - Ram

Name: Ram (ラ ム)
Age:
18 (Arc + 5)
17 (Arc 1-4)
Height: 154 cm (5'1 ")
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Ram is seemingly self centered and does things at her own pace, however in actuality she maintains a distance from people to ascertain them. She believes that Roswaal is the greatest and no one else is as precious except for her sister Rem. She is slightly more outgoing in comparison to the generally taciturn Rem, who generally allows Ram to take the lead in their sisterly bond.

The legend who established the group: http://psteamcommunity.yuanyoumao.com/id/Mashiro_Senpai_Shiina

MyAnimeList[myanimelist.net]
Wikipedia[en.wikipedia.org]
Ram[rezero.wikia.com]