It could be about a thief who writes a love letter to Riki. Maybe it involves a story where the thief has some sort of connection or affection towards Riki and expresses it through this letter in the context of a fan - created story.
The main characters are most likely the thief and Riki. The thief is the one writing the love letter, so they are a central figure. And Riki is the recipient of the love letter, making them also a key character in this fanfiction.
Some fanfictions explore the theme of loyalty. They might face situations where they have to choose between each other and something else, like a different team or a personal ambition. And the way they handle that, staying loyal or having to work through a moment of doubt, is a common plotline. Also, the theme of discovery, like finding out new things about each other that they didn't know before, can be quite prevalent in these fanfictions.
You are the aurora in my eyes, my exclusive possession.
I want to hold your hand one day to toast the guests.
I want to walk together with you.
The stars are bright everywhere, depending on whether you look up at them.
I want to walk with you in spring, hold your hand, and enjoy the beauty of flowers together.
You are my sunshine, my little happiness, my everything.
I want to sleep with you every day until forever.
You are my dream, my hope, my future.
I want to travel with you and enjoy the beautiful scenery on the road.
I want to share every bit of life with you and spend a good time together.
I want to watch the sunset with you and feel the beauty of the dusk together.
You are my treasure, I am willing to give up everything for you.
I want to grow old with you until our hair turns white.
I want to go to every place with you and see the beautiful scenery of the world.
I want to share happiness and difficulties with you forever.
You are my everything, and I am willing to give up everything for you.
I want to take a walk with you at night and enjoy the quiet night.
I want to spend every festival with you and enjoy happy times together.
I want to travel with you and explore the unknown world.
I want to sit by the window with you and enjoy the scenery outside.
I want to eat with you and taste the delicious food together.
I want to share the joy of life with you and create beautiful memories together.
I want to walk through every hill with you forever.
I want to share everything with you forever.
I want to spend every beautiful moment with you forever.
I want to walk with you on a rainy day and feel the moisture of the rain.
I want to enjoy the beauty of nature with you in spring.
I want to go to the beach with you to enjoy the beauty of the sea breeze.
I want to share my dream with you and realize it together.
I want to go to every place with you until the end of the world.
I want to share the joy of life with you and create beautiful memories together.
I want to grow old with you forever.
One idea could be a story where the reader is a new student at Shindou Takuto's school. They accidentally bump into him in the hallway, and from that moment, he becomes intrigued by the reader. As they start to interact more, they discover they have a shared love for a particular sport or hobby, which brings them closer together.
Develop the reader's backstory. If the reader has moved around a lot because of their parents' jobs, it can create a sense of longing for a stable relationship like the one they might develop with Shindou Takuto. This backstory can also be used to explain why they might be hesitant or eager in different situations in the fanfiction. Their past experiences shape their reactions to things in the present story.
I'm not sure about specific shindou takuto x kirino ranmaru fanfiction titles off the top of my head. However, you could try looking on fanfiction.net as well. Maybe start by using the search bar and typing in both of their names. Look through the summaries of the stories that come up to see if they match what you're looking for in terms of the relationship between the two characters.
Well, you can try searching on some popular fanfiction websites like Archive of Our Own. There might be various stories with this 'love letter thief x maid' theme there.
There could also be a sidekick or accomplice of the love letter thief. This character could add more depth to the story. For example, the sidekick might be trying to convince the thief to come clean to the maid about his feelings. As for the maid, she might have a best friend or a family member who plays an important role. They could be the ones who notice the maid's distress when she realizes her letters are being stolen and encourage her to find out who's behind it.