The 2SB1378 transistor is documented in this 44.3 KB PDF; the _E suffix in the name is unexplained and may denote an edition or language version. Japanese JIS numbering classes 2SB parts as PNP low-frequency bipolar transistors. Although indexed as a schematic, it is a single-part datasheet useful for checking pin assignments, package outline, voltage and current limits and gain before a replacement is fitted. Open it with any PDF reader and compare against the marking on the board.
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.