Seiko Ayase

Seiko Ayase is Momo Ayase's grandmother and the spiritual mentor whose influence gives DanDaDan's supernatural world its emotional foundation — the person who was dealing with spirits long before the story begins.

Background

She has spent decades working as an exorcist, navigating encounters with spiritual entities that most people would prefer to believe don't exist. Her approach is matter-of-fact in the specific way of someone who has been dealing with something long enough to develop perspective on it: the supernatural is real, it requires management, and the most useful response to it is practical engagement rather than either fear or denial. This orientation is what she passed on to Momo — not just the knowledge but the baseline assumption that the paranormal is something you deal with, not something that deals with you. That inheritance is the most significant thing Seiko contributes to the story. When Momo and Ken Takakura begin encountering the layered supernatural threats that drive DanDaDan's plot, Momo's ability to engage with them as problems to be solved rather than horrors to be survived comes directly from what her grandmother modeled. The series positions Seiko as the generation that handled things without the allies, tools, or particular circumstances that Momo eventually assembles — someone who did what needed to be done with what was available.

Skills

Skill	What it does
Spirit Communication and Exorcism	Developed over decades of practice, her ability to identify and engage spiritual entities is grounded in experience rather than raw power; she has accumulated understanding of specific types of entities and how to deal with them effectively
Practical Spiritual Knowledge	The body of lore and technique she built up and transmitted to Momo — not just methods but a worldview that treats the supernatural as knowable rather than inherently terrifying

Personality

Warm in the direct way of someone who has organized their life around being useful to the people they care about, and composed in the specific way of someone for whom composure is a professional requirement rather than a personality trait. Her relationship with Momo is the warmest thing in a series that operates at high speed and high volume; the grandmother-granddaughter connection is the emotional anchor that makes Momo's chaos feel grounded.

Relationships

• Momo Ayase — the granddaughter whose confidence in dealing with the supernatural comes directly from Seiko's influence; the inheritance is specific and practical, not just emotional, and the series returns to it as the explanation for why Momo is the way she is

Role in the Story

Seiko is DanDaDan's argument that the people who prepared the ground for the extraordinary things the series depicts matter even when they're not present for those things — that the training, the worldview, and the demonstrated possibility of someone who came before are what make the protagonist capable of what the story needs her to do.