An adaptation of a story from volume 10.5 about Iroha Isshiki. 

After accepting a weekend invitation, Hachiman Hikigaya accompanies Iroha Isshiki around the Chiba Prefecture to brainstorm ideas suitable for an ideal date with Hayato Hayama. As the duo wanders from place to place without a plan, they seemingly enjoy each other's company. Yet, through these straightforward and sincere interactions, the meaning behind what it means to be genuine continues to intrigue Hachiman and his outlook for the future of the Volunteer Service Club and its members. 

(Source: MAL Rewrite) 

Note: Bundled with the limited edition of the Yahari Game demo Ore no Seishun Love Come wa Machigatteiru. Zoku PlayStation Vita game from 5pb.

My Teen Romantic Comedy SNAFU TOO! OVA