Labelled 2SC2405_E, this 54 KB PDF is associated with the 2SC2405 NPN transistor. The 2SC prefix follows the JIS naming standard, and the _E suffix is not explained by the file name itself. Despite the schematic category, the content is most likely a datasheet covering ratings, characteristics and package outline. Use it to verify the pinout and limits before substitution, and to check that an equivalent part from another maker is truly compatible in the circuit.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @cyberlanelectonik. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.