Warning! Spoilers ahead for Kaiju No. 8 chapter 53!
Mikasa Ackerman's portrayal in Attack on Titan will always be one of the critically acclaimed series' few major downfalls, but Kaiju No. 8 's take on her, Kikoru Shinomiy, is already an upgrade due to one change; she's not obsessed with the protagonist.
In addition to how her true feelings for Eren Yeager in Attack on Titan didn't surface until almost literally the very end, Mikasa's only real familial attachment was with Eren. As such, she only really feared losing him and no one else, a dynamic that only intensified when she was unable to give up on Eren even after his ostensible betrayal. Her steadfast loyalty to Eren only served to strengthen her character, especially when his attempt at pushing her away failed spectacularly. But her character would have been much more dynamic if she actually had a real family she cared for. Mikasa was only Eren's adoptive sister, after all, and for the longest time, she believed her entire family was deceased. Ironically, when other family later entered her life including Levi Ackerman and Kiyomi Azumabito, she rejects them in some form. Mikasa never truly forgives Levi for his obsession with hurting her beloved Eren and she refuses Kiyomi's pleas to save herself at the onset of the Rumbling because it would involve leaving Eren and her comrades. Because she had no relatives whom she truly cared for besides Eren, there were less chances for her to be negatively affected by a major event or tragedy.
The new manga Kaiju No. 8 not only remedied this failing with Kikoru Shinomiya early on, but just introduced a tragic event that will impact her character immensely in future chapters. Kikoru might still have a father named Isao who cares deeply for her, and when his life was first put in peril just a few chapters ago, Kaiju No. 8 exacerbated their family dynamic with a flashback of Kikoru's mother Hikari and her death. Essentially, Isao's role was to ensure Kikoru had a childhood while Hikari focused on fighting kaiju. But after Hikari's death, Isao took over Hikari's role and focused on eliminating kaiju, rising to the top position of the Defense Force that fights against kaiju.
All this comes to light during his confrontation with the so-called ninth kaiju and when he comes to the conclusion that he failed his daughter, he ostensibly dies when the kaiju fuses with him. His apparent death obviously affects Kikoru in Kaiju No. 8, as chapter 53 sees her staring in disbelief as the battle rages on. She will not only suffer from his apparent ing, especially as she is destined to behold his corpse once more when the ninth kaiju returns, but all of Isao's regrets have now fallen on her shoulders. It's also very unlike her character to be completely hopeless. Kikoru is an overly prideful and capable fighter who has proven herself to be one of the Defense Force's best fighters despite being a new recruit. Her prowess hasn't gone unnoticed, either, as she was recently assigned to the first and most powerful Defense Force unit and given a special weapon when that honor is usually only bestowed upon commanders. Seeing how much the death of Kikoru's father has changed her character just further underscores the importance of family in manga.
Like Mikasa of Attack on Titan, Kikoru has her own version of Eren Yeager that she cares deeply for. But unlike her, Kikoru Shinomiya is currently suffering and undergoing a major change in character because of the supposed death of her father, a form of intense conflict that Mikasa Ackerman never experienced.
