AnkiMobile allows you to use non-system fonts on your cards. To set them up, the desktop client is required. Please see the section in the desktop manual for more information.
Please note that AnkiMobile has to load the entire font into memory in order to use it, and fonts for Asian languages can be quite large. If you have an older device and notice AnkiMobile crashing frequently after installing a font, you may have exceeded your device’s memory limits.
We have had reports from one user that no more than 3 fonts could be embedded - this may be a limitation imposed by the system web libraries. If you need access to lots of fonts, you may want to look at installing the fonts into iOS instead.