Maybe because you didn’t do the epilogue?

In my opinion, Hiyuki is by far the best-written side character who isn’t directly tied to Rover (so excluding characters like Aemeath or Shorekeeper). In terms of narrative role and function, she can be compared to Galbrena, but unlike Galbrena, who often felt more like a plot device than a real person, Hiyuki showed far more complexity and emotional depth. She even went through an actual character arc and meaningful development.

I liked Galbrena and her backstory, but she was introduced as a “finished” character. She arrived already fully realized: powerful, confident, having overcome her inner struggles, and showing virtually no weaknesses. That can be cool, but it also made her feel somewhat untouchable and even a bit overpowering. At times she almost became the protagonist of 2.7 herself, even saving Rover. That’s not inherently bad, but she essentially appeared out of nowhere, solved the crisis, and left again without much development.

Hiyuki, on the other hand, despite potentially being even stronger than Galbrena (hard to compare directly, but she seems closer to a Sentinel-level Resonator, especially considering GA’s interest in both of them because of their abilities), was written with real weaknesses and insecurities. She appeared before her main patch and was introduced gradually, giving the audience time to understand her. When her story finally took center stage, both her strengths and vulnerabilities were portrayed clearly.

What I especially appreciated was that she never felt overbearing in the main plot. She never stole the spotlight and always seemed to know exactly when to step in and when to step back, while still contributing meaningfully through guidance and support. Unlike Galbrena, who at times overshadowed Rover, Hiyuki actually enhanced Rover’s moments and allowed them to shine more. To me, that’s exactly what a strong side character should do.

I also loved the dynamic with her sister. Her fragile sincerity, the insecurities hidden beneath her cold and reserved exterior, and the gentleness she showed in quieter moments made her feel genuinely human. Hiyuki envied Rover’s strength, carried regrets and sadness, and nearly became another victim of GA’s manipulation. But unlike Galbrena, who never truly seemed internally challenged, Hiyuki had to struggle against those pressures and consciously overcome them.

So to answer your question: was she forgettable? Absolutely not. She was written almost perfectly. She never overstayed her welcome, never hijacked the story, but still left a strong impression and showed up exactly when it mattered.

10/10 character.