Shūya's Mother (Jun Yasaka)

Quick Facts

A brilliant engineer who vanishes from the page yet dominates the story, Jun Yasaka is the estranged mother whose absence forges her son’s identity and fuels the novel’s central tragedy.

• Role: Estranged mother; off-page catalyst of the plot
• Occupation: Electrical engineer, PhD-track researcher
• First appearance: Recalled only through Shūya’s memories and secondhand reports
• Key relationships: Son Shūya Watanabe; former colleague-turned-husband Professor Seguchi; schoolteacher Yūko Moriguchi
• Motifs: Absent creator, conditional love, intellectual merit as moral worth

Who She Is

Jun is less a flesh-and-blood parent than a formative idea: a mother who trains, measures, and abandons. The novel withholds a physical portrait, allowing her to exist almost exclusively in Shūya’s recollection—an ideal of intellect whose approval he must earn and whose departure leaves a permanent vacuum. Her choice to leave the family recasts maternal care as conditional, hinging on achievement rather than affection, and becomes the schema through which Shūya interprets love, worth, and punishment. Through her, the story probes the damage wrought by exceptionalism elevated above empathy, making her central to the theme of Motherhood and Family Dysfunction.

Personality & Traits

Jun’s defining qualities—brilliance and drive—are sharpened into something destructive by resentment and detachment. She recognizes potential in her son but translates care into coaching and coercion, binding love to performance. When domestic life obstructs her work, that frustration curdles into blame—and then into violence.

• Intellectually brilliant: A gifted electrical engineer pursuing advanced research, she treats intellect as the sole reliable currency of value, grooming Shūya to “accomplish the things [she] was never able to.”
• Ambitious and uncompromising: Seeing marriage and motherhood as impediments, she divorces and leaves, reorienting her life entirely around research and professional recognition.
• Abusive, with blame as doctrine: In Shūya’s memories, disappointment becomes daily beatings and a mantra of fault—“If it weren’t for you,” she says, as punishment turns love into a conditional contract.
• Emotionally detached and transactional: After leaving, she severs contact, remarries, and starts a new family. When confronted with Shūya’s crimes, she dismisses him as a failure—final proof that, for her, worth was always contingent.
• Idealized yet hollow in memory: Deprived of bodily detail, she survives in a single late image—smiling radiantly beside Professor Seguchi—an icon that obliterates Shūya’s fantasy of her private suffering.

Character Journey

Jun does not change on the page; the reader witnesses instead the collapse of Shūya’s narrative about her. Early on, he frames her as a tragic genius forced by circumstance to abandon her calling—and, by extension, him. As his confession in Chapter 5-6 Summary unfolds, he undertakes a pilgrimage to her university, where Professor Seguchi reveals she has remarried and is expecting a child. A single photograph—her “smiling so happily”—replaces the myth of the tormented mother with the reality of a woman who simply moved on. The “arc” is epistemic, not moral: Jun remains constant, while Shūya’s understanding shatters, exposing the gap between what he needed to believe and what was true—a rupture at the heart of Perception vs. Reality.

Key Relationships

• Shūya Watanabe: Jun is simultaneously Shūya’s maker and unmaker—source of his intellect and architect of his emptiness. Her promise to “come running” if anything happens becomes the script for his violent spectacle, an attempt to convert catastrophe into attention. His crimes are not random; they are performances engineered to meet her standard and compel her gaze.

• Professor Seguchi: As colleague and later husband, he embodies the world Jun chose—research, recognition, and a new family. His calm disclosure of her happy, expectant life refutes Shūya’s belief that he was a necessary sacrifice for her genius; he was, to her, dispensable.

• Yūko Moriguchi: The teacher who contacts Jun about Shūya’s crimes becomes the unwanted messenger—and, later, the conduit of Jun’s final rejection. Moriguchi’s report back to Shūya—that his mother is relieved to have left him—transforms Jun’s silence into explicit disavowal.

Defining Moments

Jun’s presence is felt through decisive absences and offstage revelations that redirect the plot’s momentum.

• Abandoning her family: Leaving her marriage and child to resume research installs performance as the condition for love. Why it matters: It gives Shūya both his life’s project (earning her) and his rationale for harm (forcing her return).
• The revelation of her new life: Learning she has remarried and is pregnant annihilates Shūya’s sustaining myth of her private devotion. Why it matters: The disproof triggers his catastrophic plan to bomb the school—if love won’t return freely, he will engineer an emergency.
• Cold dismissal after Moriguchi’s call: When told of Shūya’s crimes, Jun labels him a failure and expresses relief at leaving. Why it matters: This final, explicit rejection replaces the “come running” promise with a terminal no, sealing Shūya’s descent.

Essential Quotes

You’re a very smart boy, Shūya. I’m counting on you to accomplish the things I was never able to.

This blessing doubles as a burden. Jun converts love into a mission statement, assigning Shūya a life’s work defined by her unrealized ambitions; affection is measured in outcomes, not intimacy.

Shūya, you know I’ve had to promise that I won’t come see you, or call, or even write to you. But I’ll be thinking about you all the time. Even though we’re going to be apart, you will still be my one and only child. If anything should happen to you, I’ll forget about the promise and come running to find you.

A mother’s vow becomes a catastrophic instruction. The promise of rescue reframes danger as currency: if Shūya can engineer “anything” grave enough, he can purchase her presence—an emotional logic that underwrites his later violence.

You figured out long ago that she doesn’t want you anymore. — Mizuki Kitahara to Shūya

Mizuki articulates the truth Shūya cannot admit: Jun’s absence is not tragic fate but choice. The line punctures his narrative of noble sacrifice, forcing the reality that his mother’s indifference preceded—and perhaps enabled—his crimes.