Musashibo Sugaki was a legendary character. He was a monk soldier at the end of the Heian era and one of the traditional representatives of the Japanese Bushido spirit. However, the search results did not mention any specific information about the Musashi Bou tattoo. Therefore, according to the information provided, I don't know the details of Musashi Bou's tattoo.
Since I don't know this particular story, it might be a story that is specific to a certain community or area. It could be about a relationship between a Kabuliwala (someone from Kabul perhaps) and a Bengali woman. But without more information, it's hard to tell the full story.
I'm sorry, I'm not familiar with the specific 'kabuliwalar bengali bou' story. It might be a relatively unknown or regional story. You could try to find it in local libraries, ask local storytellers or search in specialized Bengali literature resources.
Unfortunately, without more context, it's difficult to provide the full story of 'bou kotha kou'. It could be a name of a story within a small community or an emerging piece of literature. If you could give some more details like where you heard it from or what kind of story it is (e.g. a love story, a mystery) it would be easier to answer.
It could potentially be a story about identity. The Kabuliwala may have his own identity shaped by his Afghan origin and the Bengali bou by her Bengali culture. Their story could explore how they maintain or change their identities while being involved with each other. Also, it could touch on themes of acceptance, where they either accept or struggle to accept each other's differences.
As I don't know the story, I can't say for sure. But likely the main characters are the Kabuliwala, who might be a trader from Kabul with his own cultural background and way of life, and the Bengali bou, who would represent the local Bengali culture and traditions.