Boss: Rider of Shinjuku Ch6 (Shinjuku)

Enemy Layout

Fatal Battle 1/1		404,998 Rider of Shinjuku
		213,420 Rider of Shinjuku

Drops	Claw of Chaos (Pt 1) Mystic Spinal Fluid (Pt 1) Rider Monument x1 (Pt 2)
Rewards	Saint Quartz x1

Rider of Shinjuku
	HP	404,998
	LVL	72
	HP	213,420
	LVL	72
	Class	Rider
	NP Bar
	NP Type	ST
	Actions	3 per turn
	Traits	Beast, Humanoid, Heaven or Earth, Male, Servant, Evil, Weak to Enuma Elish

Effect		Flames of Anger: At the start of every turn, reduce HP for all enemies and allies on the field by 500.
Skill 1		Monstrous Strength B: Increase own ATK (2 turns).
Skill 2		Fallen Demon A+: Increase own DEF (1 turn) and Critical Rate (2 turns).
Break		None
NP		Frieren Scharfrichter: Grant self Sure Hit and deals damage to a single enemy. Chance to apply Death. Evade does not work!

The second round of combat against Rider of Shinjuku commences. Luckily nothing changed with our cute little dog, except now the street is on fire while the defense down is no longer a part of the fight.
Each turn, every Servant on the field has 500 of their HP drained - fairly debilitating for defense-heavy compositions.
To recap, the following characteristics are still relevant:

The combination of Monstrous Strength and Fallen Demon makes his normal attacks very dangerous and unpredictable. Do not underestimate his non-NP turns. A Taunter who can take his normal attacks for other teammates is a good investment.
Rider of Shinjuku’s Noble Phantasm will grant a 1 turn buff that ignores Evasion prior to dealing damage. Beware, as common Assassin Servants used to counter him often have Evasion. However, Invincibility still works!
While Evade does not work against Rider of Shinjuku when his Noble Phantasm is up, it is still extremely useful during his other turns as his normal attacks can deal a significant amount of damage.
There is actually no special ability or effect that triggers on breaking his first HP bar.
His Noble Phantasm has a slight chance to inflict Instant Death even if it is blocked (through Invincibility). Having a strong backline can be quite crucial in case of an unlucky RNG streak. Guts status is also another way to further improve party’s survival rate against Rider of Shinjuku.

With Assassins being both evil (bonus bond points, whoo!) and ideal against Rider of Shinjuku, relying on a powerful (support) Assassin is usually sufficient. Berserkers are quite potent too, but Rider of Shinjuku has a habit of critting unprotected Berserkers.
If Masters choose to field Berserkers, be sure to pick those that either can burst extremely hard to finish the battle as quickly as possible, or ones that have better survivability to ensure they stay on the battlefield. Alternatively, bring taunt Servants to redirect the Rider's offense.
Jack's damage and utility are highly effective here, while her Evasion can be used for offense and/or during turns in which he doesn't NP.
First Hassan is a more durable option that can more easily survive the enemy's NP. He is also capable of trashing the boss by his lonesome with some minimal support if need be.
Mash, Jeanne or Taunt Servants are very effective if survival is an issue. Caster Supports are still powerful, but may fall quickly if focused.