Chaldea is notified of a new Singularity that they can't specifically pinpoint the location of, so they just send in the protagonist and a few Servants to check it out. Upon arriving, the party still can't identify the tropical archipelago they just landed in. They decide to help the adorable green creature being chased by a fishman and after defeating the monster, find out these green creatures are dubbed the "Con" by their defenders the Trung Sisters and their village is under constant attack by fish monsters. Learning this, Chaldea resolves to help the sisters in their quest to stop the Con from being eaten.
Tropes:
- Bilingual Bonus: Con is Vietnamese for 'child', which is fitting considering that they are basically a village of children.
- Call-Back: Mechanically speaking, this event reuses the first summer event's island building mechanic with a variety of new building options based on the expanded Servant roster from the last five years.
- Company Cross References: Amakusa suggests that they create holy weapons for the Con to use to fend off sea monsters. The result is miniature replicas of Ciel's pile bunker form for the Seventh Holy Scripture.
- Cuteness Proximity: Pretty much everyone becomes affectionate for the Cons because of how dang adorable they are, with Morgan, Lambda, and the Trung Sisters as the most notable examples. Morgan spends most of her time playing with a Con that wandered off to where she set up camp, Lambda becomes very fond of a Con who loves her dancing, and the Trung Sisters were the first to defend them from being eaten.
- Foreshadowing: Morgan figures out the nature of the Cons as designed to be eaten before the other Servants do, commenting that eating them would be "repulsively beneficial".
- Late-Arrival Spoiler: Though it only requires clearing the second Lostbelt to play, there is a spoiler for the Sixth Lostbelt in that Habetrot and Morgan are friends.
- Scenery Gorn: When the seas subside, it reveals that the seafloor is not natural earth, but instead a massive blob of eyed meat that is the Feng.
