Yue
Yue is the most important waifu and the very strong vampire princess from Arifureta From Commonplace to World's Strongest. Hajime finally saves her after she has been locked away in the abyss for hundreds of years. Their meeting is meant to be, and it changes the whole series. She is his main love interest and the source of his magical power. Most female leads just blush and look away, but Yue knows exactly what she wants. She keeps Hajime grounded in his humanity while happily killing any monster or enemy that gets in their way.
Her design is spot on for the classic gothic vampire look. She has beautiful long blonde hair, bright red eyes, and a small frame that makes her look really cute. But don't be fooled by how cute she looks. She is a monster with old magic. In terms of personality, she's a top-tier kuudere to everyone else but very loving with Hajime. Her scenes where she sucks blood definitely go too far into ecchi territory, and the show really plays up her mature appeal. People in the community love her because she doesn't use any of the slow-burn romance tropes. She just openly claims her man and stays fiercely loyal, which makes her the queen of all her fans.
When you look for Yue wallpapers, you'll mostly see two different styles. There are stunning magical action shots of her casting deadly spells with a completely blank face. Then there's the huge collection of beautifully drawn, highly suggestive ecchi fanart that shows her more intimate, seductive moments. Her gothic outfits make her look either really cool or really cute, and her blonde hair and red eyes make for beautiful desktop backgrounds.