06 typically points to the specific file or volume within that box.
"Yola Nakagawa 0217-06 Min" isn't a single "thing," but a to a specific piece of history. It likely represents an official record or a minute-sheet involving an individual named Nakagawa in the Yola region. Yola Nakagawa 0217-06 Min
If "Nakagawa" is the primary subject, this could be a reference to a passenger manifest or an immigration file (often found in Brazilian or American archives, where Japanese immigration was significant) that has been cross-referenced with a location or vessel. 06 typically points to the specific file or
Many records regarding West African administration use this exact naming convention. If you are researching the administrative history of Yola, this would be a reference to a specific minute-sheet from a colonial office file. Yola Nakagawa 0217-06 Min