Introduction[]
In My Hero Academia, Tenya Iida with Recipro Burst moves several meters at the time that Stain's sword was a few centimeters from cutting Todoroki. I'll be calculating his speed with Recipro Burst.
Calculation[]
First we need to measure Todoroki's elbow.
Scan 1
Todoroki = 176 cm
Todoroki's elbow = 12.32 cm
Todoroki's head = 30.09 cm (We'll use this later)
Now we can measure the distance between him and Stain's sword.
Scan 2
Todoroki's elbow = 12.32 cm
Distance = 2.36 cm or 0.0236 m
Then we have to measure the distance that Iida moved.
Scan 3
Todoroki's head = 30.09 cm or 0.3009 m
Panel height = 8.15 m
Distance = 0.3009*8.15/[0.3009*2tan(70/2)] = 5.82 m
Finally we can find his speed. In the low-end we're going to assume Stain was moving at Peak Human speeds (12.51 m/s).
Low-End = 5.82/0.0236*12.51 = 3085.09 m/s
In the high-end we're going to assume Stain's sword was moving as fast as the fastest baseball bat swing recorded (55.39 m/s).
High-End = 5.82/0.0236*55.39 = 13659.74 m/s
Final Tally[]
Tenya Iida's Recipro Burst Speed (Low-End) = 3085.09 m/s, Mach 8.99 - Hypersonic (Accepted)
Tenya Iida's Recipro Burst Speed (High-End) = 13659.74 m/s, Mach 39.82 - High Hypersonic
This calc was considered an outlier here.