What can you do as a free member?

Member benefits illustration

Create your free account today and unlock all our premium features and tools to enhance your gaming experience.

Member benefits illustration

Create your free account today and save articles to your watchlist and get notified when they're updated with new information.

Member benefits illustration

Create your free account today and save your favorite games for quick access later, synced across all your devices.

Member benefits illustration

By creating a Game8 account and logging in, you'll receive instant notifications when someone replies to your posts.

Comment rating feature illustration

By creating a Game8 account and logging in, you can make use of convenient features in the comments section, such as rating and sorting comments.

Premium archive feature illustration

By creating a Game8 account and logging in, you can access Premium articles that are exclusively available to members.

Site Interface

Guest
Free Member
Article Watchlist
Game Bookmarks
Cross-device Sync
Light/Dark Theme Toggle
User Profiles
Direct Feedback
Comment Rating

Game Tools

Guest
Free Member
Interactive Map Access
Interactive Map Pins
Interactive Map Comments
Interactive Map Pins Cross-Device
Check List
Event Choice Checker
Deck Builder Cross-Device
Message Board Notification
Message Board Cross-Device
Build Planner
Stat Calculator
Diagnostic Tool
Weapon/Armor Wishlist

Want more information?Learn more

Shin Megami Tensei 3: Nocturne (SMT Nocturne)

How to Open Locked Door in Mantra HQ

5
Add to Watchlist

Shin Megami Tensei III Nocturne - How to Open Locked Door in Mantra HQ.png

This is a guide to opening the Mantra HQ prison door in Ikebukuro for Shin Megami Tensei III HD Remaster (SMT Nocturne). Read on to learn how to open the door in Ikebukuro as well as the rewards inside!

List of Contents

How to Find the Locked Door

The Door is in the Mantra HQ Prison

Ikebukuro Door Location

The door can be found just after all the prisoner cells in the Mantra HQ Prison. The Prison itself is in the B1 level of the Mantra HQ Building.

Speak to the Incubus demon prisoner next to Isamu's cell, and he will direct you to the locked door.

Can only be Accessed After Beating Thor

Thor Boss Fight

The door can only be accessed after the Thor boss fight when you first arrive at the Mantra HQ.

After you beat the boss, players will be allowed to explore the Mantra HQ Building. Simply take the elevator or the stairs down to the basement to find the prison.

How to Beat Thor

How to Open the Locked Door

You need 24 Base Strength

Opening the Door

In order to open the locked door, players will need 24 points in the Strength Stat. This is base Strength which means that any bonuses from Magatamas will not be counted.

Players without 24 Base Strength will have to level-up and invest in the stat to open the door. For a tips on how to level-up quickly, visit our Best Leveling Areas page!

What Does Strength Do

Locked Door Rewards

Cache Cube with the Gaea Magatama

Gaea Magatama Reward

There will be a single Cache Cube behind the locked door. It will have the Gaea Magatama inside it. The Gaea Magatama is a good Physical Magatama which greatly resonates with the required stat to open the door. This is one of the best Magatamas to have for physical builds.

Gaea Magatama Stats

Shin Megami Tensei III: Nocturne Related Guides

Tips and Tricks

Tips and Tricks

All Tips and Tricks

Tips and Tricks
How to Get Raidou How to Get Dante
How to Heal and Revive Demons How to Recruit Demons
Fusion Calculator Guide How to Farm Lucky Tickets
Rag's Jewelry Shop Build Guide: Best Demi-fiend Stat Builds
How to Fuse Demons Mystical Chests Guide: List of Mystical Chests
What is the Kagutsuchi List of Evolving Demons
Best Leveling Areas How to Unlock the Compendium
Joining the Mantra: Gozu's Question List of Trophies and Achievements
How to Get Deathstones How to Return to the Amala Labyrinth
Fiend Bosses List and Locations How to Open All Kalpa Doors
Burial Chamber Guide List of Shady Brokers
Junk Shop List New Game Plus Features : How to Unlock NG+
Beginner Guides
Press Turn Battle System Guide Differences Between Difficulty Settings
How to Swap Demons How to Talk to Demons
How to Change Voice language How to Save Game
How to Remove Curses How to Farm Macca
Stat Guides
Stat Guide: All Stats Explained What Does Strength Do
What Does Magic Do What Does Agility Do
What Does Vitality Do What Does Luck Do
Faqs
Where to Find Bill Should You Release Pixie
Jumping from Mantra Headquarters Demi-Fiend Canon Name
How to Open the Door in Ikebukuro Four Oni Locations

Comment

3 Anonymous Anonymous almost 3 years

bro me too wtf

2 Anonymous Anonymous almost 4 years

It opened for me with 25 base strength. No magatama equipped that increased my strength.

See more comments (5 Comments)

Author

SMT 3 Nocturne Walkthrough Team
This article was created by Game8's elite team of writers and gamers.
    Leave feedback(Login required)
    Please participate in our site
    improvement survey
    12/2025
    Would you assist in
    improving Game8's site?
    ×
    This survey will take about 1 minute.
    Your answers will help us to improve our website.
    We are listening to our users' valuable opinions and discussing how to act on them.
    The information collected through this survey will be used for the purpose of improving our services. In addition, the information will only be disclosed a part of a statistic in a format that will not allow identification of personal information.
    Begin Survey
    Not Now
    ×
    Please rate each item regarding Game8.co's Advertisements.
    Amount of Ads
    Very Dissatisfied
    Somewhat Dissatisfied
    Fine
    Somewhat Satisfied
    Highly Satisfied
    Placement of Ads
    Timing of Ad Display
    Ad Loading Speed
    Safeness of Ads
    Content of Ads
    ×
    Please rate each item regarding Game8.co's Quality of Articles.
    Amount of information
    Very Dissatisfied
    Somewhat Dissatisfied
    Fine
    Somewhat Satisfied
    Highly Satisfied
    Frequency of updates
    Speed of new information
    Accuracy of articles
    Understandibility of articles
    Readability of sentences
    ×
    Please rate each item regarding Game8.co's Usability of the Site.
    Ease of finding information
    Very Dissatisfied
    Somewhat Dissatisfied
    Fine
    Somewhat Satisfied
    Highly Satisfied
    Loading Speed
    Use of Color
    Font Size
    Visibility of Images
    Easy to Understand Layout
    ×
    Please rate each item regarding Game8.co's Message Boards, Comments.
    Ease of Writing
    Very Dissatisfied
    Somewhat Dissatisfied
    Fine
    Somewhat Satisfied
    Highly Satisfied
    Readability
    Ease in Finding Information
    Comment Quality
    Comment Quantity
    Admin Response
    ×
    Please rate each item regarding Game8.co's Site's new design.
    Please rate our site's new design
    Very Dissatisfied
    Somewhat Dissatisfied
    Fine
    Somewhat Satisfied
    Highly Satisfied
    Do you think that the website's design change makes the site easier to use?
    Has the new design made it easier for you to find information on the site?
    Has the new design improved the overall visual appeal of the site?
    How would you rate your overall satisfaction with the new design of the site?
    ×
    How likely are you to recommend Game8 to someone you know?
    Very Unlikely
    0
    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    Very Likely
    If you have other opinions regarding potential improvement to the website, please share them with us. We would appreciate your honest opinion.
    Note: This is a free response section, so you can proceed without entering anything.
    Note: Please be sure not to enter any kind of personal information into your response.
    ×
    Thank You
    ×
    Thank you for participating in our survey! Your answers will help us to improve the quality of our website and services.
    We hope you continue to make use of Game8.
    Close
    For other opinions or comments, go here.

    Rankings

    Popular Articles
    Message Board
    • We could not find the message board you were looking for.

    Gaming News

    Pokémon Legends Z-A Exclusive Café Donuts Hint At Two Legendaries Returning For Mega Dimensions DLC

    Pokémon Legends Z-A Exclusive Café Donuts Hint At Two Leg...

    Popular Games

    Recommended Games

    All rights reserved

    ©ATLUS. ©SEGA. All rights reserved. ATLUS is registered in the U.S. Patent and Trademark Office. ATLUS, the ATLUS logo, SHIN MEGAMI TENSEI, SHIN MEGAMI TENSEI NOCTURNE and SMT are either registered trademarks or trademarks of ATLUS Co., Ltd. or its affiliates.
    ©CAPCOM CO., LTD. All rights reserved.

    The copyrights of videos of games used in our content and other intellectual property rights belong to the provider of the game.
    The contents we provide on this site were created personally by members of the Game8 editorial department.
    We refuse the right to reuse or repost content taken without our permission such as data or images to other sites.

    SMT 3 Nocturne Walkthrough & Guides Wiki

    Quick Access
    Guide Index

    Story Walkthrough

    Main Story

    Ending Guide

    Labyrinth of Amala

    DLC Dungeons

    Boss Guides

    Story Bosses

    Maniax / Chronicles Only Bosses

    Mini-Bosses

    Optional Bosses

    Demons

    Demons By Race

    Magatamas

    Skills

    Items

    Puzzle Boy Guides

    Tips and Tricks

    Stat Guides

    News

    Characters

    Atlus Wikis