Mirror
The tag "mirror" gathers a surprising amount of anime art. It looks like a prop: a character checks their reflection before school or a fight. However, anime mirrors have more meaning than that, so they are in almost every show, from slice-of-life to dark psychological thrillers.
Kagami (鏡) the Japanese word for mirror holds cultural significance in Japan. The holy mirror Yata no Kagami, one of Japan's three Imperial Regalia, was used to summon Amaterasu from hiding. Japanese stories use mirrors to symbolize truth, revelation, and the divine. Japanese anime often features broken mirrors that do not match the person looking into them or magical mirrors that act as portals or oracles during identity crises. Regularly, dark fantasy and psychological horror shows do this. A common scene in slice-of-life character art is someone brushing their hair or fixing their collar in front of a mirror.
Wallpapers cover all that. Some pieces are neat and stylish, and the mirror makes the character look like two people, making a nice portrait. Some are more atmospheric, with broken or dark mirrors adding tension. Mirrors naturally frame character and reflection, which often leads to some of the tag's most intriguing compositions.