How to Obtain
During the event, Saury can be obtained, substituting the normal ship drop. They will drop more commonly in comparison of the Hishimochi, but will require you to have an appropriate equipment set up to collect the Saury.
On top of that, most fish will only be found within fishing zones on certain maps when the music "Saury Festival at the Naval Office" cues in.
Be warned that overfishing can result in gaining less fish in due time.
Fishing Zones in the following maps
Saury will drop in various fishing zone locations, some will drop within fishing zones of EO of the Naval Base Waters and the Northern Waters which will grant a high chance of gaining saury while other locations outside of EO will grant a chance to gain Saury when the new BGM cues.
1-1
1-5
Exchange
Saury Quests
Isokaze Drop Locations
Along with the update, Isokaze will become available as a normal drop in the following locations: