No.9326300 ViewReplyOriginalReport
just occured to me when seeing a picture of Usa with a Bunny Ear attire that her name means Bunny Ears if transliterated to English. Take that with Kagami Kuro (literally Black Mirror) and you can have a link in Japanese mythology to the other characters in the trio depending on how interpret things. There is a popular new years treat in Japan known as Kagami Mochi, and I don't know how many people have heard of the Rabbit in The Moon Legend, but it features a Rabbit pounding Mochi on the moon, the rabbit in this case would be Usa. There is also the Yata No Kagami, which is one of the three Imperial Regalia of Japan, and Kokonoe Rin can be translated as Dignified Imperial Palace.

Also of note is that the characters sort of resemble the symbolism of the Imperial Regalia. Usa would be the Yasakani no magatama (Jewel) representing Benevolence and Emotion (She's endless kindhearted and caring), Rin would be the Kusanagi (grass tooth blade) representing Willpower and Valor (She's always there to defend her friends and can easily stand up to the adult characters) and Kagami would of course be the Yata No Kagami (Mirror) representing Wisdom and Honesty (She is seemingly the most world wise and she is straight up with how she feels about things and always makes her voice heard).