A full walkthrough and guide for the Keeper of the West sidequest in Shin Megami Tensei V (SMT 5). Read on to figure out where to find the sidequest, how to complete it, and what rewards you can receive.

Keeper of the West Location

Koumokuten is located on top of a small building west of the Kamiyacho leyline fount. To get there, you'll need to climb up a hill coming from the north.

Note: This quest will only be available after completing the sidequest The Ancient Guardian.

Keeper of the West Sidequest Information

How to Complete Keeper of the West

Objectives
1	Talk to Koumokuten, located on top of a small building west of the Kamiyacho leyline fount. To get there, you'll need to climb up a hill coming from the north. Note: This quest will only be available after completing the sidequest The Ancient Guardian.
2	Koumokuten will engage with you in battle. Defeat Koumokuten to complete the quest. ・How to Beat Koumokuten
3	Defeating Koumokuten will reward you with 1 Large Glory Crystal, 70000 EXP, and 1 Koumokuten's Essense.

How to Beat Koumokuten

Recommended level: 65
Enemies	Weak	Block	Resist
Koumokuten

Negate Status Debuffs Koumokuten Casts on Your Party

At the get go, Koumokuten will start debuffing your party using Marakunda and Masukunda. It is crucial your negate these status debuffs as you are basically being renderred weak and vulnerable to its attacks. Use a skill like Dekunda to negate any debuff done on you and your allies.

Hit with Electric, Block Against Force

Use Electric spells to hit Koumokuten's weakness to gain turns, and have a party that blocks Force to make Koumokuten lose his turns. Having a good healer and conserving MP will ensure your survival.

Don't Hesitate to Debuff Koumokuten

While Koumokuten has skills that can debuff you, it does not have other Support skills that can negate debuffs you cast onto it. Use skills like Tarunda and Rakunda to lower Koumokuten's attack and defense respectively, to make it more vulnerable to your attacks.

Full Guide:
How to Beat Koumokuten

Shin Megami Tensei V Related Guides

List of Subquests and Rewards

Vengeance Subquests

Subquests
Prince of Her Dreams	In Pursuit of Knowledge
Brawny Ambitions	She Who Rules the Night
Knocking on Death's Door	Beastly Battle of Wits
Home Sweet Home	To New Horizons
Picture-Perfect Debut	Essential Research
Brawny Ambitions II	Infiltrate the Demon Feast
Tough Love	Pixie on the Case
As God Wills	A Self of My Own
Part-Time Gasser	Lighting the Way
Reclaim the Golden Stool	Liberate the Golden Stool
A Star is Born	Shinjuku Jewel Hunt
The Disgraced Bird God	The Vampire in Black
The Hunter in White	Alice's Wonderland
Devotion to Order	Heroes of Heaven and Earth
The Serpent King	The Great Adversary
Supersonic Racing	Classified Courier
Song of Nostalgia	Guide to the Lost
Rite of Resurrection	Heroes of the Celts
The Guardian of Light

List of SMTV Vengeance Subquests

Da'at: Minato

Subquests
A Preta Predicament	No Stone Unturned
Bully Breaker	Pollution Panic
The Spirit of Love	The Water Nymph
The Cursed Mermaids	The Demon of the Spring
To Cure a Curse	The Gold Dragon's Arrival
The Benevolent One	The Ultimate Omelette
Talisman Hunt	Movin' on Up
Keeper of the West	The Succession of Ra

Da'at: Shinagawa

Subquests
Chakra Drop Chomp	Those Seeking Sanctuary
Holding the Line	A Wish for a Fish
Magic from the East	Can I Keep Them?
Iced Out	Kumbhanda's Bottle
Birds of a Feather	The Tyrant of Tennozu
The Root of the Problem	A Goddess Stolen
The One I Love	The Falcon's Head
Keeper of the South

Da'at: Chiyoda

Subquests
The Path to Myojin Forest	Lighting the Way
Black Frost Strikes Back	A Sobering Standoff
Stones of Malice	One Mokoi's Trash...
He of a Hundred Hands	An Unusual Forecast
A Power Beyond Control	The Search for Oyamatsumi
Clash with the Kunitsukami	The Horn of Plenty
Roar of Hatred	Glitter in Ginza
The Angel of Destruction	The Ancient Guardian
Keeper of the East

Da'at: Taito

Subquests
On Bended Knees	Downtown Rock 'n Roll
The Egyptians' Fate	A Princess in a Pickle
In Defense of Tokyo	The Raid on Tokyo
A Need for Nectar	Abaddon's Assault
Keeper of the North	The Bull God's Lineage
An Incentive for Incense	The Destined Leader
The Holy Ring	The Sleeping Sands
The Winged Sun	Fionn's Resolve
A Universe in Peril

Empyrean

Subquests
The Seraph's Return	The Red Dragon's Invitation
The Noble Queen	The Wrathful Queen
The Compassionate Queen	A Plot Revealed

DLC Quests

DLC Subquests
A Goddess in Training	The Doctor's Last Wish
The Rage of a Queen	Return of the True Demon
Sakura Cinders of the East	Holy Will and Profane Dissent