Nendo could be a great addition. His simple - minded yet loyal nature can add some humor and unexpected twists. For example, he might accidentally almost expose Saiki's powers while trying to be helpful in a situation involving Teruhashi.
Yan Bingyun and Shen Wan 'er were characters from the novel " Celebrating Years." Yan Bingyun was a spy sent by the Qing Kingdom to Northern Qi, and Shen Wan 'er was the eldest daughter of Northern Qi. Shen Wan 'er did not know Yan Bingyun's true identity at first, but she gradually fell in love with him. However, Yan Bingyun did not have any sincere feelings for Shen Wan 'er. He was only using her to obtain information about Northern Qi. Even so, Shen Wan 'er's feelings for Yan Bingyun were very deep. There was no clear description of their ending in the literature.
Well, in fanfiction about Saiki Kusuo and Teruhashi, often their relationship is explored in really interesting ways. Sometimes it shows Teruhashi's attempts to get closer to Saiki in a more comical way compared to the original series. And Saiki, with his unique powers, might react in different and unexpected manners.
In the manga, Saiki doesn't have a romantic ending with Teruhashi. The focus is more on Saiki's supernatural powers and the humorous situations he gets into rather than a traditional romance.
Maybe you haven't found the right type of literature yet. There are so many different genres out there, like science fiction, mystery, or even graphic novels. Try exploring different styles and you might change your mind.
Look for books that are related to your hobbies or interests. For example, if you like sports, there are many sports - themed novels. This might make reading more enjoyable for you.
Another theme is the idea of Teruhashi trying to break through Saiki's emotional barriers. Since Saiki is often aloof, Teruhashi's attempts to get closer to him form a major part of many fanfics. It can be really entertaining to read how she tries different strategies to get his attention.
One popular theme is the 'unlikely couple' aspect. Given Saiki's introverted nature and Teruhashi's popularity, the idea of them getting together is an interesting concept. Another theme is the comical misunderstandings. Since Saiki has psychic powers and Teruhashi is always trying to be perfect, there are a lot of opportunities for misunderstandings that lead to humorous situations.
Perhaps the development of the characters felt forced or the overall storyline was too predictable. Maybe there was a lack of depth or complexity that you look for in a manhwa.