Well, first of all, check out some well - known fanfic platforms. AO3 is a great place to start. They have a large collection of fanfics from various fandoms. Another option is Wattpad, although it has a wider range of content including original works. Type the title carefully into the search function of these platforms. Also, some smaller, more niche fanfic communities related to the series that Cure Black and Cure White are from might also be a place to look, but those might be a bit harder to find.
You could try searching on popular fanfic websites such as Archive of Our Own (AO3) or FanFiction.net. Just type in the exact title 'cure black cure white first fanfic' in their search bars.
Chapter 349, "Attempting to Cheat, East Ridge's Strength, Lu Yang's Tactics", is the clearest early answer because it turns East Ridge's situation into a concrete plot event. It opens with The five people, including Zhu Tong, were all bowing their heads at... and closes on Bringing only Zhao Hu and three others over, how could he rest.... The key payoff is that the chapter closes with Seeing the five leaders' eyes all gathered on him, a faint gleam flashed in the depths of Lu Yang's eyes.
Chapter 126, "The Production Team Actually Played Dirty on This?!", is the clearest early answer because it turns Director Sun's situation into a concrete plot event. The chapter turns that into something concrete by moving from Wen Jiaojiao initially wanted to cause trouble.
Chapter 48, "All the Bitter Teas Have Been Taken Away", is the clearest early answer because it turns Director Sun's situation into a concrete plot event. A useful checkpoint is the way the scene starts with He Yun felt guilty for initially ignoring Jiang Li on purpose, and...
Chapter 179, "I Want Plastic Film", is the clearest early answer because it turns Shang Shaojing's situation into a concrete plot event. The chapter gives readers a real answer by opening on Everyone originally had no expectations for the gifts that Su Yinwan...
Chapter 197, "Dear Brother", is the clearest early answer because it turns Sister Li's situation into a concrete plot event.
Chapter 236, "The Murderer Returns to the Scene of the Crime Theory", is the clearest early answer because it pushes Northeast Rift Valley into a new phase or setting. Early on, The short-haired youth beside them chimed in, "That's right, senior,....
Chapter 175, "He Tampered with the Food", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event.
Chapter 387, "Hello everyone, this is my disciple", is the clearest early answer because a shaky connection becomes usable in the plot. It opens with Liu Suqing V: "Even if we meet, I wouldn't recognize, faces covered...
Chapter 196, "I am the one with the most potential!", is the clearest early answer because it turns Wen Jiaojiao's situation into a concrete plot event.
Chapter 22, "Number 7203", is the clearest early answer because it turns Xiang Hao's situation into a concrete plot event. Early on, Hearing this, Su Yinwan looked at Shang Shaojing with a face full of.... By the end, Jiang Li's righteousness temporarily shut Jiang Yan up, but after a....