>>535160915
It's because you'll want to make a good Seiun parent to inherit this ultimate onto your non-Seiun front runners, 4 seconds of acceleration for your last spurt is just disgusting.
Seiun herself is a good front runner because she can keep the lead with Hold Your Tail High proccing with Vanguard's Spirit, Escape Artist, and another middle leg skill. Her stat growth is a bit shitty but she makes up for it with her skills and parent potential.