Helps you learn a foreign language for a example Japanese. The first screenshot is of a dictionary I convert from EDRDG's Jmdic_en using the mdict builder included in mdict-java.
The e-dictionary format Mdict with it's extensions of mdx and mdd appears several years ago as a 'database format' for Mdict PC.
This App is based on the open-sourced library Mdict-java，and is completely free of charge and with zero advertisement.
To use copy over .mdx as well as .mdd files to /sdcard/PLOD/mdicts and then relaunch or you can pick the main folder in the drawer.