Is it permissible to clarify the meaning of Japanese character names in a story to show that they are not among the religiously prohibited matters, and is it permissible to learn the Bushido characters to avoid using them in character names?

Writing fictional stories is permissible if the intention behind them is to encourage virtues and promote good morals. This is based on what has been narrated from the Children of Israel regarding wonders recounted for entertainment, not for proof, and what was intended as parables, admonitions, and lessons in bravery, whether attributed to humans or animals.

Regarding clarifying the meaning of the character's name and stating that there is no Sharia-related prohibition in it, there is no issue with that.

As for learning Bushido characters, if it does not lead to deviation or being influenced by anything that contradicts Islamic law, then there appears to be no impediment to it.

The questioner is advised to disregard obsessive thoughts and stop preoccupying herself with them.