Layla Prismriver vs Kuroyoru Umidori: who would win?

Kuroyoru Umidori favored — Slight edge (~55%)

Layla Prismriver · Touhou Project · Base

Tier

8-B

Attack Potency

City Block Level+

Speed

Average Human

Durability

Human Level

Kuroyoru Umidori · Toaru Majutsu no Index · With Extra Arms

Tier

8-A, up to 7-C

Attack Potency

Multi-City Block Level, up to Town Level

Speed

Peak Human, up to Supersonic

Durability

Street Level, up to Town Level

A heuristic estimate from normalized VS Battles Wiki stats: tier, attack potency, speed and durability.