In most graph database, you find a vertex by filtering its properties, e.g. Gremlin graph query language. In Unicorn, you can do the similar with document vertices (it is, a vertex corresponding to a document in another table/collection). This is probably very nature in a business application. However, it is not very useful in your case as your vertices are abstract without any properties.

I guess what you want is some large scale graph analytics, which I suggest Spark GrpahX or other distributed graph computing engine.

Unicorn is designed for property directed multi-graphs.