In Her Defense

“

Oboro stands deathly still, as if listening for something.

— In-game description

Rewards

The quest coordinates are deceiving - you actually need to find the dock storehouse and talk to Byakubu at (X:21.2 Y:26.6) to enter, then you are teleported to the quest location.
The coffer contents are the Artifact Armor for Heavensward, which is Item Level 210 former Allagan Tomestone of Esoterics gear. The coffer was added to this quest with the launch of Stormblood. The rest of the set is available at Yolaine in Foundation (X:13.1, Y:11.9) for Centurio Seals.

In a voice barely above a whisper, Oboro tells you the storehouse is surrounded. The blades in the shadows are no doubt loyal to Redway, waiting to attack you when you are most vulnerable. Oboro bids you give them a target, by patrolling and pretending to /doze, then striking back.

Though Oboro had come up with a plan to sneak across to Hullbreaker Isle, the recent attack on the storehouse has changed his mind. If Redway has seen fit to send assassins to your hideout, no doubt unfriendly eyes watch the docks, as well. Oboro reasons the wisest course of action now is to see what opposition awaits you, and asks that you join him at the Moraby Drydocks.

Crouched on a battlement, you and Oboro look out over the harbor in dismay. There are too many guards to fight. However, your friend is not without a plan. He supposes that since it is you who is bound by duty to save Princess Yuki, he is therefore free to put himself at risk and draw Redway's attention. This will allow you to sneak across the channel in the boat Jacke has provided. Retreat to Oschon's Torch and wait for your moment.

Redway has gleefully captured Oboro, and left with his men. After pacifying an agitated Akagi, the two of you resolve to infiltrate the Truehounds' camp on Hullbreaker Isle. Speak with him at the Moraby Drydocks.

You have spoken with Akagi. Approach him again when you are ready to board the boat to Hullbreaker Isle.

Rosalinde promised the captive vassals freedom in exchange for the treasures of the Yatsurugi clan. However, the captain goes back on her word when Princess Yuki brings them, and orders her bound and stowed with the other prisoners. Just as all hope seems lost, you appear with Akagi. Princess Yuki finally commands you to rescue her. You draw your daggers, slash Oboro's bounds, and take the fight to Redway. When the sellsword realizes he is losing, he makes to run─only to meet a gory end on Rosalinde's axe blade. After the battle continues, you finally put an end to the cutthroat captain's reaving for good. Their leader dead, the remaining Truehounds run, leaving behind all the treasures of the Yatsurugi clan. Princess Yuki offers her heartfelt thanks, and then turns excitedly to her freed vassals. With the profits from these treasures, her lands can be rebuilt. Oboro indicates it is time to take your leave. Speak with him in the dock storehouse.

Oboro congratulates you for the successful completion of your first mission. Truly, few other shinobi could have earned their master's trust as you earned Princess Yuki's. Now, he bids you meditate upon your experiences, and continue upon the path towards mastery of the art of ninjutsu.