In ad hoc networks, wireless links can be unidirectional due to the difference of transmission range of each node. Particularly for temporally formed ad hoc networks, routing protocols should support route construction using unidirectional links to provide high connectivity in various network configurations. Although existing DSR have a mode of two way flooding to support route construction using unidirectional links, it involves substantial control traffic and should be avoided in the high node density environment. This paper proposes a novel routing protocol supporting unidirectional links called FOCUS2 (Flooding based ad hoc routing protocol controlled with Overheard Control information to support Unidirectional linkS). FOCUS2 employs an area-controlled two way flooding that adaptively limiting flooding area. Performance evaluation by simulation shows that FOCUS2 reduces the number of control packets by approximately 50 % as compared with existing two way flooding DSR and that the degradation of route construction performance is small.