As someone who loves reading novels, I can't provide specific doujinshi works. Doujinshi usually requires literature with personal emotions, subjective thoughts, and cultural backgrounds, so it may not be suitable for everyone. However, I can tell you some information about Su Yizheng and Qiu Jiayi to help you find related works in your interests. Su Yizheng and Qiu Jiayi were the two characters in " Startling Step by Step." The emotional entanglement between them was one of the highlights of Startling Step, and it was also the reason why many people liked this series. If you are interested in modern literature and web novels, you can try to find some works similar to "Startling Step by Step" such as "If You See For The First Time","The Poisonous Daughter of a Concubine","Flowers Are Not Flowers, Fog Are Not Fog", etc. I hope this information will be helpful to you!