Titan-Android by David Wu.
From the webpage:
Titan-Android is a port/fork of Titan for the Android platform. It is meant to be a light-weight implementation of a graph database on mobile devices. The port removes HBase and Cassandra support as their usage make little sense on a mobile device (convince me otherwise!). Gremlin is only supported via the Java interface as I have not been able to port groovy successfully. Nevertheless, Titan-Android supports local storage backend via BerkeleyDB and supports the Tinkerpop stack natively.
Just in case there was an Android under the tree!
I first saw this in a tweet by Marko A. Rodriguez.