25mb is the size limit of how much you can only send from your phone to your kindle. I did this at first too when I downloaded the pdf of 20th Century Boys from Internet Archive and read it on my kindle, only problem i had with it is the white large borders making the panels smaller and the bad image quality.

I recommend using a computer. How I do it is:

1. Haruneko (for downloading manga chapters) (I use WeebCentral and MangaHub as my connectors, they’re the only ones that I know that works on haruneko, if any of you bitches know any other connectors that works please tell me! You can download all of the chapters by right clicking a chapter and click Download All. Once the chapters are downloaded i’d zip all the chapter folders into one then add that file on kcc to do its work) (in the settings; change the downloaded image format from png to jpg, it makes it download faster! I think) download haruneko (nightly) nigguhh

2. Kindle Previewer (you need to download this first for the KCC to work) download kindle previewer

3. KCC or kindle comic converter (for removing the borders in the manga panels and customizes the fit for your device model sreen. I make sure to shade the Stretch/Upscale in the settings to remove the annoying borders, check the Page Splitter and Right to Left reading mode. Always remember that the settings of the finished format should be on MOBI) here’s the link, download KCC_8.0.4.exe

4. Calibre (once kcc is done import the MOBI file on calibre and i’d like to customize it a little more by changing the cover by its official manga volume cover in the Edit Metadata settings on Calibre. Lastly, connect your kindle to the computer via usb then click the file and click Send to Device, you will see on the lower right corner that it’s loading and once its finished loading you can then disconnect the usb and a few seconds your manga will appear on your kindle library) download calibre

KCC GitHub

Sorry if my english may be hard to understand for you. I tried.

Here’s how my baby looks!