It depends. If the portrayal of the yandere girlfriend is done in an interesting and nuanced way, it could be appealing. But if it's overly stereotypical or one-dimensional, then no.
One common theme is possessiveness. The yandere sister usually shows extreme possessiveness towards her brother or the main character. She doesn't want others to get close to him.
A gift from her in a yandere manga can have multiple meanings. It could be a sign of the yandere's obsessive love, an attempt to control the situation, or a way to create drama and tension in the story. Sometimes, it might even be a red herring to mislead the reader.
One common theme is overprotectiveness. The yandere little sister will go to extreme lengths to protect her loved one, often seeing others as threats. Another theme is possessiveness. She wants to have the sole attention of the person she's fixated on, like in many stories where she gets jealous of the protagonist's friends. Also, there can be themes of secrecy and hidden desires, where she hides her yandere tendencies until certain events trigger her extreme behavior.
Sister Devil Manga was an original manga created by Iida Shiki. The story told the story of the siblings after the protagonist met the demon. The manga was serialised in Kadokawa Bookstore's "Electric Shock G's Comic" and was published by the same name. Sister Devil's manga was still in the midst of being serialised, and the author was Iida Shiki. The latest chapters and complete works of Sister Devil's manga can be found online on the relevant websites.
Well, such a girl is often obsessive and possessive. She might go to extreme lengths to keep the person she likes close to her, sometimes even using violence or threats.
Well, 'A Sister's All You Need' also has elements related to the yandere sister concept. In this light novel, the sister's character has a certain possessiveness towards the main character, and through various events, it unfolds a story full of humor and family - like emotions.