What funding is available for undergraduate research in Japan? I wish to go to Japan for a semester-long research internship in the field of robotics. I am a Canadian citizen.

However, I am having a hard time finding what funding I can actually apply for.

I know the JSPS fellowships are out of question as they only apply to postdocs.
MEXT fellowships are out as well because they are only for a full 5 years.

What funding is available for undergraduate research in japan?
@Kayan and @fkraiem have provided links for general (undergraduate) fellowships in Japan. You'll note that most provide tuition and a living stipend (as well as airfare / language training in some cases).

What these fellowships do not provide is research funding -- if by this you mean equipment and supply costs. They will not provide funds if you want to build a robot, run experiments, or even to buy a laptop/Raspberry PI.

This is because research grants for equipment purchases go to university professor- and researcher-run labs. If you want to do research in robotics, you should write to professors/researchers and ask them if you can study in their lab for a year under the various scholarship/fellowship programs listed by the other respondents.