Most dictionaries give the hyphenated form,
hara-kiri, but Macquarie has it as one word, and Wiktionary allows that as an option. In use, both are quite often seen. In contemporary periodicals the word is mostly used in a figurative sense. Often this is in a sporting context, as in this sentence from a cricket report on the India TV News website in January this year:
But then, all hell broke loose as Lungi Ngidi and Kagiso Rabada ripped apart the Indian line-up in just 11 balls even as the harakiri of the batters also contributed to the crazy collapse.
At least, I suppose the batters didn't ritually disembowel themselves, but I don't follow the cricket closely.
I'll add
harakiri as a rare word.