You can register a legal alias (通称名) that you can use on forms. I know people who have done this with just single a single kanji to avoid a lot of the headache

You can register a legal alias (通称名) that you can use on forms. I know people who have done this with just single a single kanji to avoid a lot of the headache associated with having a foreign name or (god forbid) a middle name. I've considered a few times registering my legal alias as 一一 to have a two stroke full name.