WARNING: The following contains spoilers for Episode 5 of SSSS.Dynazenon, "What's Lover-Like Mean?," now streaming on Funimation. It also contains discussion of suicide.
SSSS.Dynazenon has devoted a lot of its runtime towards developing Yume’s character, and with good reason. The other cast members undoubtedly have their own emotional hangups and mysteries, but Yume’s is the most apparent. Her sister died when she was younger, and she is just now dealing with the repercussions. Some details revealed in Episode 5 will definitely continue to impact Yume’s character going forward.
Although, honestly, a pool episode is not the typical episode for these kinds of revelations. Usually, pool episodes are for fan service and a break from the action, but SSSS.Dynazenon takes advantage of the setting to drive the plot forward. Episode 5 forces Yume to confront her sister’s cause of death while revealing that it may not have been the accident she thought.
Towards the beginning of SSSS.Dynazenon Episode 5, Yume and Yomogi are in another meeting with one of her sister’s ex-classmates, one who has a video of Yume's sister smiling and singing at chorus club. This emotional moment for Yume is seemingly sidelined when Chise wins free tickets to Tokyo Beach Land, an indoor water park. Joining the Dynazenon pilots on their recreational trip is Sizumu, a member of the Kaiju Eugenicists. He invites himself after hearing Yume and Yomogi discuss the trip at school.
Sizumu’s participation prompts Gauma to attempt a capture plot. His scheme requires Yomogi to pretend he and Yume are dating. This, somehow, will confuse Sizumu, allowing for easier capture. Hijinks ensue as expected; the pilots enjoy their time in the park, Gauma’s plan fails and Yume and Yomogi spend a lot of couple time together.
The fun doesn’t last long for everyone. Yume’s blissful day off takes an abrupt turn when she sees someone falling into the water and is reminded of her sister. In her brief flashback, her sister is face down and lifeless in the stream. Yume mentioned before that her sister died at the floodgate, implying that she drowned. When she and Yomogi discuss the water park earlier in the episode, Yume is hesitant until Sizumu invites himself. She uses Sizumu’s presence to give herself a reason to go, possibly knowing she will have to confront her sister’s death once again.
Before long, Sizumu himself is drafted to control this week’s kaiju and makes a point to target the emotionally unbalanced Yume. Thankfully, support from Yomogi and Koyomi’s new combination, Dyna Soldier Striker, saves her just in time. Dynazenon then hands the Eugenicists a hefty defeat. When Yume shows gratitude to Yomogi, he's flustered by her beauty, leading Gauma to grab him by the neck and jump off a nearby cliff into the water below, joined by Chise and Koyomi.
Yume seems scared at first but relaxes into a smile. Seeing her co-pilots, the very people who risk their lives to support her, plummet into the water and come up cheerful may have helped relax her anxiety. She may have been better prepared to confront her sister’s cause of death if it weren't for what happens next. Yume receives another call about someone with information. In this meeting, the person of interest reveals that her sister may have committed suicide just before the episode ends.
Prior to this, Yume believed her sister’s untimely death to be an accident at the floodgate. Good character development may spiral into even more personal grief for Yume. As she opens up more, the team has been able to support her, but this reveal will definitely impact their cooperation going forward.