Japanese University

I am going to be entering university next year, and I was wondering what my options for studying in Japan were.
I'm currently obtaining my a-levels in the UK (History, Maths, Economics, and Geography) and since I only take a few subjects, I will not be able to pass an entrance exam.
Therefore, I would please like to ask if any one knows of any universities that allow entry with grades obtained with another countries education system.
Also, I am half Japanese and have Japanese citizenship, does this mean I won't be eligible for any sort of international student courses and schemes? Is there any sort of funding help to pay for university fees as well that I would be to take?

Thank you for taking the time to read, please let me know if you any information :)
Thank you!!

A lot of the G30 universities would be in a good position to help (http://www.uni.international.mext.go.jp/ ) - you won't need EJU or kikokushijyo for that - they can accept your UK grades directly.

However, as a Japanese citizen you won't be eligible for international scholarships such as JASSO. You would be eligible for JASSO loans, like every Japanese citizen.

日本政府（文部科学省）奨学金留学生募集要項
申請時に日本国籍を有する者は、原則として募集の対象とならない。ただし、申請時に日本以外に生活拠点を持つ日本国籍を有する二重国籍者に限り、渡日時までに外国の国籍を選択し、日本国籍を離脱する予定者は対象とする。選考は応募者が国籍を有する国の在外公館で行う。