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.
- Chekhov's Gunman: Morgan is initially shown throughout the event to be playing with a stray Con. Her knowledge in summoning is then used during the climax.
- 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.
- David Versus Goliath: A point is made that the only way to restore any Con that were eaten by the monsters is for a Con to deliver the killing blow, and the unlikelihood of such small and squishy creatures managing that is pointed out as a big problem, even with Servants to wear the monsters down to their last legs. It isn't until the Con are equipped with effective weaponry and armor that they stand a chance of getting that good hit off.
- Foreshadowing:
- In the prologue, three main servants are summoned due to the high rayshift aptitude: Ereshkigal (emphasis on Divinity), Meltryllis (emphasized affinity in water), and Wu Zetian. Morgan later uses the former three's main affinities through their hair strands as catalysts to summon Taisui Xingjun in the climax.
- 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.
- Ridiculously Fast Construction: Provided that you have the sufficient number of Cons, they can quickly build anything ranging from swords and pilebunkers to colony ships as residences.
- 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.
- Schmuck Bait: Quite a few monsters are able to get the Con due to taking advantage of their naivety and innate attachment to new things. The kelpie are just so cool to look at that they have to ride them, damn it, and the rusalka are just so pretty as singers and dancers they have to get in closer. The solution of course is to provide things to the Con that are even cooler or more entertaining such that they aren't tempted.
- Turtle Island: The Singularity at first is told to take place in the back of a turtle that had grown massive, with the elder turtle who is taking care of the village being a terminal for the turtle. However, it is later revealed that the island is actually a massive Feng who simply has taken the shape of a turtle.
