it means aurora publishing was part of ohzora publishing. AKA this japanese publisher is the parent company based in Japan and they incorporated a subsidiary company in America to publish titles in english and not specifically their own titles but just licensing and doing business like a regular American publisher but by law they are the subsidiary of ohzora publishing.

It's all business terms but bottom line is ohzora publishing owned aurora. Most likely they were not making money and they discontinued the subsidiary which equals disposal of the company and I bet the workers out of jobs decided to start a new company and negotiated with ohzora to finish selling their back editions.

Now they are their own company with no affiliations with Ohzora which is a pretty big blow considering the fact that it would be harder for them to negotiate contracts without the backing of a japanese parent company. I just assume this is the case but we'll see!