I'm not entirely sure as I haven't read this specific fanfiction. But it might involve Kushina's presence inside the seal in Naruto's body and some sort of unique interaction or adventure that takes place within that sealed space. Maybe she imparts some special knowledge or power to Naruto.
The main characters are Naruto and Kushina. Given that it's about Kushina inside the seal within Naruto, their relationship and interactions would be at the heart of the story. It's possible that other characters from the Naruto universe could play supporting roles. For example, the Nine - Tails might also be important as it is also associated with the seal. But overall, Naruto and Kushina are the key figures in this fanfiction.
Toge Inumaki is important too. His special cursed speech ability makes him stand out. Also, the principal of the school, Masamichi Yaga, is likely to be important as he is in a position of authority and has an influence on Gojo and the other students. There could be other characters like the members of different clans that also play roles in the complex web of the story.
The recognition of the seal character seal could be achieved by using the seal mouse recognition app. First, he clicked on the mouse recognition app on his phone's desktop. Then, he chose the first option of "Picture Identification" in the Zhuan Shu app. After entering the next step, he chose "Take a Picture" or select a picture to identify. The software would automatically recognize the simplified Chinese characters corresponding to the seal characters in the picture.