Level 200 is required to 100% the game, as the achievement "MMOs that use a level system are unfair that way" requires it.
The achievement description says you need Level 150, this is incorrect, as the achievement descriptions are taken from the Vita version but the achievement criteria are taken from the PS4 version, leading to this mixup.

https://www.youtube.com/watch?v=eugSo_7eqy8

This video demonstrates an average run, gaining approximately 150k EXP in two minutes. If you can consistently manage this rotation, you can earn 4.5mil EXP an hour.

For reference, that will get you from Lvl200 to Lvl210.

First, some background information on how the EXP mechanics work in Hollow Fragment.

Base experience gain from mobs is approximately 10 EXP, and is effectively irrelevant for levelling up as you'd need to kill tens of thousands of enemies.

If you want to level up you need to fight enemies at least ten levels higher than you, as you get a 400 EXP bonus per level. This caps out at a 4000 EXP bonus, and this is essential to levelling up.

Use enemy radar and make sure all the enemies on the map are the darkest colour icon, which means they are at least ten levels above you. Enemies in a map have a small level range, so you'll start to lose EXP gains as soon as the lowest level enemy in the map is no longer 10 levels above you. For example, the bees in Beedance Sprawl range from 156-162 in Normal MP, meaning you should change areas at Level 147.

You also gain a boost of up to 50% EXP on top of this by killing enemies quickly with sword skills, which means you want to finish off enemies with sword skills as much as possible. If you aren't targeting the enemy you defeat with a sword skill, the timer doesn't seem to start, so you always get 50%. This makes AOE sword skills very good for EXP grinding.

The EXP required per level consistently increases from level 100-220, and then switches to a different formula for 221-250.

For 100-220, it follows the following pattern;


Formulaic ramblings below;


For 221-250, 221 has a requirement of 552,500 EXP and you just add 2500 EXP per level. 222 = 555,000, 237 = 592,500, etc.
This continues to at least 251, I haven't been able to confirm if it follows the same pattern all the way to 300.

The Experience charm (Floor 86 shop), the Clover Ring (Floor 93 shop) and the Fairy Cape (Floor 93 shop) all have the "EXP Up" effect, which increases EXP gain by 10%. This can be stacked twice, for a 20% increase.
Ideally, you should equip the Infinity Ankh charm (purchased on Floor 76 after defeating the Floor 98 boss but before defeating the Floor 99 boss) as it's the most powerful piece of equipment for any of these slots, and then use the Clover Ring/Fairy Cape for EXP Up.
The Searching skill tree gives you two EXP boosts - 10% from the passive skill, and 15% from the active skill "Gain EXP".
EXP Flagons and Grand EXP Flagons give a temporary boost of 15% and 25% respectively, and are great for Method 1 as you're rotating through mobs constantly.

Accuracy is crucial, because you will be attacking enemies far above your level and constantly missing your attacks.

Either Demonspear: Gae Bolg (spear) or Demon Blade: Gram (2H Sword) are ideal, as they have the True Strike effect and cannot miss. These are acquired through Implements, and Gram is effectively a requirement for efficient grinding due to the AOE power of the 2H Sword skills. You can also craft the rarity 6 rapier Championfoil which has a True Strike effect, but I'd still recommend Gram.



If you don't have either of these, the Perfect Style skill from the Precision skill tree gives you temporary True Strike and CRT Up Lvl 2 for 60 seconds.
The 2H Sword Skill Meteor Fall gives 20 seconds of True Strike, use this at the start of your OSS.
ACC potions can also be purchased from vendors and give you True Strike and CRT Up Lvl 2 for 60 seconds.

Perfect Style + ACC potions allow you to chain True Strike casts together, but Perfect Style has a 240 second cooldown and you can only carry 10 ACC potions at a time, so it won't last for long. These are great for getting the first few levels done, but it's not worth going past Level 150 without a True Strike weapon.

• Weapon - Demonic Sword Gram. 2H Sword skills are the best for AOE, and this weapon has True Strike meaning it will never miss. Demonspear: Gae Bolg (Spear) and Championfoil (Rapier) also have True Strike, but their movesets aren't as good for AOE.
  
  
  
  
• Head - Ace Pendant. Good buffs for all six main stats, no downsides.
  
  
  
• Body - Legion Storm Jacket. This gives you the Attacker role (increased damage, decreased defence) as well as a big STR buffs and direct Attack/Damage Value buffs.
  
  
  
• Arms - Crimson Gauntlets. These make your damage ignore enemy armor, in return for crippling your own defence, but the Attacker role has already put you at 0 defence so it's basically free damage. As you are attacking massively higher level enemies, this is a huge damage boost.
  
  
  
• Legs - Legion Storm Boots. These give the same STR/Attack/Damage Value buffs as the Legion Storm Jacket, and it also gives you the Soul Connect buff which is a combined movement speed/attack interval/recovery time/SP regen buff. These are the best boots in the game, and there is zero reason to ever use anything else.
  
  
  
• Back - Fairy Cape. EXP Up buff. If you don't need the buff, use the Assassin's Cloak for a significant damage increase and immunity to poison/paralysis/bleeding, in return for a massive defence decrease. Again, this is irrelevant, as we already have 0 defence.
  
  
  
  
• Waist - Assassin's Shenti. This works the same way as the Assassin's Cloak, and has no downside for our current build.
  
  
  
• Charm - Infinite Ankh gives you a massive ATK/DEF buff and small increases to every stat in return for lowering the chance of critical damage for both you and your opponents, which I'm fairly sure is completely irrelevant for this build because Crimson Gauntlets mean you ignore your opponents defence, and you have zero defence for opponents to crit though. This item is only available from the Floor 76 armor shop after unlocking Floor 99 and before beating the Floor 99 bosses. It costs 90mil Col, make sure you buy it.
  
  
  
• Ring - Clover Ring gives you a second EXP buff, and the Resonant Ring increases all attributes by 5%.
  
  

• War Cry, Last Resort, Strength and Vitality for ATK increases.
  
• Soulful Stand to increase SP, and SP Chargeto refill it.
  
• Hyper Armor gives you 30 seconds of personal invulnerability, and Protective Armor gives your entire party 30 seconds of invulnerability. Wait for the first one to expire before using the second one, or it won't work.
  
• Perfect Style for True Strike + CRT Up Lvl 2 (100% accuracy)
  
• Gain EXP is a 15% personal EXP buff.
  
• Crime Servant redirects your EXP gain to your partner.
  
• Effect Booster double the duration of abilities. This does NOT apply to buffs from Sword Skills. I tested this on Hyper Armor and it lasted 57 seconds instead of the expected 60, which is strange and worth double-checking.

Completing the "Unlock - Multiple Sword Skill Chaining with OSS" implement allows you to chain more than two Sword Skills, and (optional, but recommended) completing the Recast Reduction implements give you a combined 30% cooldown reduction.

Setting up an OSS Chain makes it easier to chain that specific order of Sword Skills by increasing the input window for the next Sword Skill, so it's worth doing this.
My preferred 2H OSS Chain is as follows;

Blast -> Lightning -> Avalanche -> Eruption -> Brawler Blade -> Astral Hell -> Meteor Fall -> Scooped

Practice this a few times in the training room to get the timing down, so you can consistently do it against enemies.

If you don't have Gram, put Meteor Fall at the start of the OSS to give you True Strike.

Playing Multiplayer (even in solo mode) will increase all enemy levels by 20 and each difficulty increases enemy levels by 50, meaning you can increase enemy levels by 20/70/120. This is useful, because it's difficult to find enemies at a high enough level for efficient grinding in singleplayer. It also lets you bring three additional partners who will also gain EXP while grinding, and allows you to grind outfit unlocks for your main partner.

Note that if you die in Multiplayer, you don't lose progress. Deaths in Singleplayer reset your progress to the last time you changed areas, deaths in Multiplayer kick you back to the hub area with no penalty.

Normal difficulty sets all the mobs to approximately level 110, Hard sets them to 160 and Death Game sets them to 210.


Look around the main square of the map, ignoring the dead ends as they have higher level enemies and there's no point slowing down when the main enemies respawn faster than you can kill them.
The bees are capable of taking out half of your health with a strong attack, so the safest way to kill them is to target one at a time and OSS chain them to death.
You can also choose the Hollow Mission "Love is Light" and trigger it, allowing you to progress any rank 1 implement while EXP grinding.
Circle around the map for as long as you want, just remember to return to the hub area and exit multiplayer to save your progress occasionally.

Normal difficulty sets all the mobs to approximately level 200, Hard is 250 and Death Game maxes all of them out at level 300.



Demonic Sword Gram is REQUIRED for this method, as well as the Protective Armor and Hyper Armor skills for temporary invulnerability. Pick the "Buffer" role in the multiplayer lobby to extend the length of the invulnerability skills from 30 seconds to 45 seconds. Refer to this guide to learn how to use the invulnerability skills efficiently.

https://cs2bus.com/sharedfiles/filedetails/?id=2077378762

There are 17 golems in the area, in four groups. Run around and aggro all of them without getting hit by any of them (you will be stunlocked to death immediately) then use Protective Armor to make your entire party invulnerable, pull them into one spot, dash backwards to and start your OSS chain. The backdash takes you out of range of actually hitting your target, so you can complete the entire OSS chain and kill the rest of the mobs without worrying about it getting interrupted by the death of your target. Once they're dead, exit the area to the west and teleport back to the hub area via the conveniently placed teleport stone ten meters away. This respawns all the mobs, and you can immediately teleport back and reenter the zone.

Each rotation takes about two minutes, and earns you approximately 150k EXP. At Level 200, you can gain ten levels in an hour if playing absolutely perfectly.

This strategy is very high risk, and you will die many times when you start out. if you trigger either of the hyperarmor skills while the other one is already active, it will not work, and you will die. If you get hit by any of the golems, at any point, you need to spam a hyperarmor skill immediately. If it doesn't activate, you will die. If you are caught in a sword skill when your hyperarmor runs out, you will die.

Try to position yourself next to a pillar or a wall when setting up for your OSS chain, to stop the golems from moving too far to your side and avoiding your attacks. You can't manage it for both sides simultaneously, but just one will help. I've tried luring them back to the doors, but their pathing gets confused and it's not as consistent as using a pillar.

Battle Skill Chain
Strength -> Vitality -> War Cry -> Last Resort (four damage buffs) -> Soulful Stand -> SP Charge -> Variable Storm (450SP total, and maxed out) -> Gain EXP (optionally, Crime Servant too) -> Protective Armor/Hyper Armor


Use the SP/EXP skills towards the end of the chain, as the buffs given by Sword Skills will overwrite your earliest buffs when you start your OSS.

Make sure to praise your partner during the OSS chain, to reduce ability cooldowns and restore your SP - both effects are useful here.

If 99% of XP gain relies on your enemy being a higher level than you, what's the most efficient way to grind out these last ten levels? Two 1H swords with EXP buffs for as much flat EXP gain as possible? Suffering through the 1000xp per mob to get that final level, which will probably need about a million EXP?

I leave this as an exercise to the reader.