My Fiancé Fell in Love with My Older Sister. After Locking Myself in My Room for Five Days, 500 Years Had Passed

• Author: Gorogoro Mikan
• Genres: Romance Fantasy, Fantasy Phương Tây, Chuyển Sinh, Light Novel
• Status: Ongoing
• Rating: ★ 4.2 / 5
• Published: 2026-10-02

A Beginning Born from Betrayal

The story opens with a painful twist as Felicia, a young Duchess, faces a cold confession from her fiancé. Felix bluntly declares his love for her older sister, Agnes, dismissing their own bond as a mere twist of destiny. This betrayal by those closest to her strikes a devastating blow, pushing our protagonist to the brink of despair.

Yet, in that moment of agony, a mental defense mechanism kicks in. Felicia suddenly reclaims memories of her Past life, granting her a fresh perspective on her current situation. Rather than crumbling under Felix's rejection, she begins looking for a way to break free from the chains of a loveless union.

Her initial goal is very simple: lock herself in her room for five days to calm down and plan how to convince her father to agree to the Cancellation of engagement. She wants to start a new chapter, escaping the shadow of betrayal and the favoritism everyone always showed Agnes. But fate takes a turn no one could have anticipated.

A Doorway Between Eras

The story's biggest turning point occurs when Felicia's Magic spirals out of control due to the clash between her old memories and current energy. When she finally steps out of her room after what she thought was just five days, the world has moved on. Five centuries have passed while she was tucked away, completely unaware of the passage of time.

This jump isn't just a leap in time; it's a clean slate that wipes away her traumatic past. Everyone she knew—from the father she intended to negotiate with to her former fiancé, Felix—is now just dust in the archives of history. Felicia finds herself a stranger in a strange land, the sole survivor of a bygone era.

At this point, the narrative shifts from the typical gloom of a Romance Fantasy betrayal to a journey of discovery and survival. She must navigate a world of unfamiliar social norms, advanced technology, and a changed Magic system after half a millennium. It’s a refreshing twist that helps the story escape the usual clichés of courtly romance.

An Independent and Intelligent Heroine

Felicia isn't a damsel in distress waiting to be rescued after her heartbreak. Armed with an Accounting degree from her Past life, she possesses a logical mind and practical financial management skills. This background gives her the confidence to rebuild her life from scratch in an unfamiliar society.

Beyond her intellect, she possesses a Unique Skill known as Presence Concealment. This ability does more than just keep her safe; it’s incredibly effective for intelligence gathering and reconnaissance. It reflects her new mindset: moving from someone who was constantly scrutinized to someone who chooses to remain hidden while observing the world.

Felicia's resolve to find her own happiness is evident in her decisive actions and her composure in the face of massive change. She is no longer haunted by the shadow of Agnes or the sting of Felix's betrayal. Instead, she focuses on unlocking her own potential and enjoying the freedom she’s finally found after 500 years of slumber.

Highlights Worth Experiencing

• The concept of a 500-year jump due to Magic out of control brings a refreshing twist to the Other World genre.
• The protagonist, Felicia, possesses a compelling combination of modern Accounting knowledge and specialized combat abilities.
• Her approach to dealing with betrayal is constructive, focusing on self-reliance rather than dwelling on revenge.
• The new world 500 years later is revealed with significant potential for exploration and building new relationships.

A Few Points to Consider

• The opening chapters can feel quite heavy as they dwell on the betrayal by Felix and Agnes.
• The explanation for the rapid passage of time feels a bit rushed, which might leave some readers feeling disoriented during the transition.
• Certain aspects of her adaptation to the new world might seem a bit too convenient thanks to her pre-existing skills.

Community Feedback

• On the Narou (Syosetu) platform, it holds a score of 5,877 points (as of October 2, 2026), with readers praising the mix of psychological depth and adventure.
• Fans particularly enjoy how the protagonist utilizes her Past life expertise to handle finances and management in the new era.
• The evolution of her Unique Skill is also a popular topic of discussion on community forums.

Final Thoughts on Felicia’s Journey

This work by Gorogoro Mikan is an evocative tale of rebirth and resilience. While it starts with a familiar romantic tragedy, the 500-year leap transforms it into a promising adventure. With her sharp mind and Presence Concealment skill, Felicia is sure to keep readers on their toes.

This is an excellent pick for anyone looking for a story that is gentle yet possesses real depth regarding personal growth. Her old world is gone, but for Felicia, true happiness is only just beginning.

In short: A unique Romance Fantasy that uses a time-skip hook to celebrate a woman’s independence and intellect in the face of adversity.

Tags: strong female lead, adventure, romance fantasy