One possible fanfic could be about their journey to become better soccer players together. They might start as rivals on the team, with Ibuki's aggressive style contrasting Shindou's more strategic approach. As they train and face various opponents, they gradually learn from each other and form a strong bond both on and off the pitch.
One common theme could be the development of their relationship. Since it's fanfiction, it might explore different aspects of how they get closer to each other.
Perhaps there is a conflict within the team where some players side with Ibuki's style and others with Shindou's. This creates a rift in the team. They have to find a way to reconcile their differences not just for their own relationship but also for the sake of the team. They could start by having one - on - one conversations and gradually bring the whole team together again through their combined efforts.
I'm not sure about specific 'keita and ako lemon fanfiction' as it might be quite niche. You could try searching on fanfiction - specific websites like Archive of Our Own. There might be some works there related to your request.
Typical themes might include the relationship development between Riko and Keita. It could involve their daily interactions, how they handle the unique situation of their relationship in the context of the 'kiss x sis' story.
Love and family are common themes. Since they are in a rather unique family situation, many fanfictions explore how they navigate their love for each other within the family context.
You can try fanfiction.net. It has a large collection of fanfictions from various fandoms, and there are likely to be some good ones for Keita x Kazuki from Gakuen Heaven there.
One good story could be 'The Bond of Keita and Kazuki'. It focuses on their growing relationship within the school setting. They face challenges together and their friendship slowly blossoms into something more.
There might be a lot of such fanfictions out there. However, without delving deep into that particular fandom myself, it's hard to point out exact ones. You could also check out relevant fan communities on social media platforms where fans might share their favorite fanfictions about Riko and Keita from 'kiss x sis'.