The following contains spoilers for Episode 4 of Engage Kiss, "Unobtainable Lingering," now streaming on Crunchyroll.
Engage Kiss is an exciting action/fantasy/sci-fi anime making its debut in the Summer 2022 anime season, taking place on a cyberpunk island metropolis named Bayron City. Protagonist Ogata Shu has more on his mind than the city's complex politics or even his rent -- he must somehow juggle the two most important girls in his life, and it won't be easy.
It won't be easy for the two girls in question, either. Kisara is Shu's powerful Demon partner in battle, while the lovely Ayano was Shu's first real girlfriend, and they both care a great deal about him. However, as Episode 4 shows, the divide between Kisara and Ayano is growing, and there is no obvious solution. Things are getting messy in a hurry.
The personal conflict between Ayano and Kisara is largely based on their mutual interest in Shu, and that feud, hinted at in Episode 3, comes to the fore in Episode 4. Every time Ayano and Kisara come face to face, they can't help but criticize or question one another and their respective roles in Shu's daily life. This goes far beyond ordinary jealousy of the time Shu spends with each of them -- this particular love triangle is based on Shu's risky career as a Demon hunter.
Shu is serious about fighting in D-disasters and getting revenge for the mysterious Demon that killed his family, but Kisara and Ayano cannot agree on how Shu should handle all this. Ayano, for her part, doesn't want to get Shu involved in any more Demon cases, seeking to protect him from the danger and violence of the job. Most of all, Ayano believes that Shu's quest for revenge is a needless risk, and that getting revenge won't do him any good anyway. Conversely, Kisara wishes to enable Shu's Demon hunter lifestyle even more, emotionally supporting him as a fighter while serving as his loyal companion in battle. She is certain that Shu deserves this chance to get his much-desired revenge. Clearly, Kisara and Ayano can't both get their way.
In Episode 4, Ayano and Kisara talk over their differences, but neither of them gains any ground. They effectively agree to disagree, and it's clear that their personal animosity has grown yet again. So far, they are not actively trying to sabotage one another, instead playing tug-of-war with Shu and doing their best to sway him to their own side. Thus, Kisara and Ayano show a little mutual respect, or at least some restraint, and it's up to Shu to decide whether Kisara or Ayano is the right partner for him. However, by choosing one partner, Shu will also validate that girl's preferences while rejecting the other. What is more important to Shu: peace and happiness or getting his revenge? So far, he seems to be leaning toward Kisara's side, but he is sympathetic to Ayano too. This isn't over yet.
Ayano also learns the grim truth of Kisara and Shu's memory-based deal -- a revelation that disgusts Ayano when she hears it. This makes the battle a little more personal for her, since Ayano, as Shu's first girlfriend, can't stand to have her ex-lover lose his memories of her. Even if Ayano can't keep Shu as her boyfriend, she at least wants Shu to remember their fond memories and act accordingly. However, Shu is forgetting his ex-girlfriend, and that may drive a wedge between them. He's doing his best to keep the peace in the face of all these tricky factors, but he's running out of time. Shu has some tough decisions to make about his career and love life alike.