The Internet Archive hosts various versions of Bleach episodes, including 1080p MP4 files for newer seasons like the Thousand-Year Blood War (though Episode 4 there may refer to Season 1, Episode 4 of that specific arc).
The most reliable and legal way to download episodes for mobile viewing is through a paid subscription to a streaming service. These platforms allow you to download select titles to your device: Download Bleach 004 mp4
If you are looking for tools to automate batch downloads from supported sites, developers have created open-source options: The Internet Archive hosts various versions of Bleach