Since I don't have specific information about 'oko sama star after story', it's difficult to say precisely. However, generally in a 'after story', it might focus on the aftermath of the main events in the original 'oko sama star'. It could explore how the characters' lives have changed, whether they have achieved their goals, and what new situations they find themselves in. For example, if the original was about a group of friends trying to become stars, the after story could be about their life as established stars, dealing with fame and all that comes with it.
Since this is a rather unknown or not widely known story, it's hard to say who the main characters are. It could be the same characters from the original 'oko sama star' if it's a direct continuation, but without more details, it's impossible to be certain.
I'm not sure specifically what the'sama sama letter day story' is about as it's not a widely known common story. It could be a very personal or a story from a specific local or cultural context.
You can start from the chapter that follows the events of the anime's ending. Usually, there are forums or fan communities that can provide specific chapter recommendations.
One great 'Maid sama story fanfiction' is 'The Unseen Moments at Seika High'. It delves deeper into the characters' relationships and adds some interesting twists to the original plot. It's really engaging as it shows different perspectives of the main characters outside of the canon story.
The 'Hachishaku Sama' story is often associated with Japanese folklore and can have different interpretations depending on the context. Some see it as a tale of mystery or supernatural occurrence.
I'm not entirely sure as it could be a rather specific or niche concept. It might be a story related to a child star ('okosama' can mean child) and what happens after a certain event in their story. But without more context, it's hard to be more specific.