Samurai Warrior

The Samurai warriors are regarded as some of the most well trained, disciplined and deadly in all of history. From every corner of the globe, anyone can become a samurai, given they can master the Way of the Sword, a very mentally and physically challenging training. Similar to Monks, samurai training can begin at any age, but it's quite common for people to begin at childhood. Training lasts for several years as they perfect not only the art of the sword, but poetry, history and mental discipline. Most samurai practice celibacy, but it's common for that rule to be discarded. 

When trainees reach the age of 13, or after 3 years of training, they are given their most hallowed weapon: the Katana. 
In the years prior, trainees were given practice short swords similar to the katana, but to be granted your own, is a moment all true future samurai cherish. Katanas can be given to trainees or other samurai at any point in life, whether as a gift, inheritance or from a will. 

Samurai rarely use stealth tactics on the battlefield. Many believe facing your opponent head on in combat is an honorable way to battle. Should they defeat someone in combat, they must kill them, to give them a good death. 

Sharp Senses

Your years of training to become a samurai have honed your skills beyond that of ordinary warriors. 
You gain proficiency in History, Perception and Intimidation. If you are proficient in 1 of these skills, you can replace it with a language of your choice. 

Warrior Stance

Samurai are deadly swordsman. 
At 7th level, you are able to enter a Stance as a bonus action, which lasts for 1 minute. Each stance has a different ability and effect. This ability can't be applied to any ranged weapons. 

Steel Stance: When taking this stance, your strength dramatically increases as you are able to add 1d8 damage of your weapons damage type to the roll. The damage increases to 1d10 at 10th level and 1d12 at 15th level. 

Lightning Stance: This stance allows you to move at unimaginable speeds. When you strike an opponent, you deal an extra 1d8 lightning damage. If there is another enemy within 10 feet of the opponent, you can choose to attack them as well (maximum of 3). The damage increases to 1d10 at 10th level and 1d12 at 15th level. 

Dragon Stance: This stance gifts you the magical abilities of a Red Dragon, engulfing your weapon in magical flames. If an enemy attacks you, you can attempt to parry the attack, adding a +2 to your AC. If you attack an opponent, you deal an extra 1d10 fire damage. At 15th level, the parry adds a +3 and the fire damage increases to 2d10.

Water Stance: When taking this stance, the spirits of fallen samurai warriors flow through your veins and weapon, allowing you to strike true against your foes. You have advantage on attacks with your weapon and deal an extra 1d10 points of Force damage. The damage increases to 1d12 at 15th level. 

Sun Stance: With this stance, you emulate the beautiful radiance of the sun as it fuels your strikes. Your strikes can deal an additional 1d8 Radiant damage. The damage increases to 1d10 at 10th level and 1d12 at 15th level. 

Moon Stance: You emulate the pale light of the moon, shrouding your movements as you strike. With this stance, you become Invisible, and are able to attack your opponents with advantage. Striking them does not reveal your position, unless you fail to hit them. 

Iron Will

Because of your remarkable skills with your weapon, you are able to treat a 19 and 20 as critical hits. 

Mask of the Demon

At 10th level, you are granted a samurai mask. Talk with your DM about how it comes into your possession. Was it a family heirloom? Inheritance? Did you purchase it from a merchant? 
The mask can look however you'd like, but the color is what you'd need to choose, for it grants you different abilities. You can only possess and wear 1 mask at a time. 

Black: You are immune to Necrotic damage and can deal 1d10 Necrotic damage as a bonus action breath weapon attack 
Blue:  You are immune to Cold Damage and can deal 1d10 Cold damage as a bonus action breath weapon attack
Green: You are immune to Acid Damage and can deal 1d10 Acid damage as a bonus action breath weapon attack
Red: You are immune to Fire damage and can deal 1d10 Fire damage as a bonus action breath weapon attack
Yellow: You are immune to the Charmed condition and learn the spell, Charm Person and can cast it once per short rest as an action
Purple: You are immune to the Blind and Deaf condition and learn the spell, Blindness/deafness and can cast it once per short rest as an action
White: You are immune to the Frightened condition and learn the spell, Fear and can cast it once per short rest as an action

Healing Spirit

Your resolve has built so far to the point, that you can heal yourself and others. 
At 15th level,  you can take an action to heal yourself or others for Hit Points equal to your Fighter level + your Constitution modifier. You can use this feature a number of times equal to your Constitution modifier (minimum of once) per long rest. Any unused Healing Spirit uses are reset after a long rest. 

Iron Will

You have become one of the greatest Samurai to have ever lived. At 18th level, you are able to overcome death itself. When you are reduced to 0 HP, you can roll a d20. If you roll a 10 or below, you pop back up with half the damage that was dealt to you (minimum of 1). If you roll above a 10, you come up with full damage dealt to you. If you roll a natural 20, you pop back up with half your total HP and are able to make an attack on any creature within 10 feet of you. You can use this feature once per long rest.