Universal Studios Japan ride reliability

1. 1Space Fantasy - The Ride11d 13h lost · 1 breakdown · down on 21 of 21 days 0%
2. 2JAWS4d 9h lost · 25 breakdowns · down on 21 of 21 days 59.6%
3. 3Jurassic Park - The Ride3d 19h lost · 21 breakdowns · down on 19 of 21 days 64.7%
4. 4Detective Conan 4-D Live Show: Jewel Under the Starry Sky2d 10h lost · 21 breakdowns · down on 21 of 21 days 75.2%
5. 5Hollywood Dream - The Ride:Backdrop2d 10h lost · 34 breakdowns · down on 21 of 21 days 78.3%
6. 6Hollywood Dream - The Ride1d 23h lost · 35 breakdowns · down on 21 of 21 days 82.4%
7. 7Mine Cart Madness™1d 16h lost · 38 breakdowns · down on 21 of 21 days 84.7%
8. 8Jurassic Park - The Ride in the Dark1d 9h lost · 1 breakdown · down on 8 of 21 days 86.8%
9. 9The Flying Dinosaur1d 6h lost · 32 breakdowns · down on 20 of 21 days 89%
10. 10Factory of Fear: Zombie Tour1d 3h lost · 5 breakdowns · down on 8 of 21 days 89.6%
11. 11Chainsaw Man: The Chaos 4-D1d 2h lost · 3 breakdowns · down on 9 of 21 days 90%
12. 12Frieren: Beyond Journey's End Story Walk -- Echoes of Adventure8h 41m lost · 22 breakdowns · down on 21 of 21 days 91.2%
13. 13Flight of the Hippogriff™13h 46m lost · 20 breakdowns · down on 19 of 21 days 95.1%
14. 14Despicable Me: Minion Mayhem6h 50m lost · 22 breakdowns · down on 21 of 21 days 97.4%
15. 15Harry Potter and the Forbidden Journey™6h 5m lost · 14 breakdowns · down on 19 of 21 days 97.7%
16. 16JAWS: Red Alert1h 59m lost · 6 breakdowns · down on 8 of 21 days 97.7%
17. 17SADAKO'S CURSE: DARK HORROR RIDE6h 7m lost · 11 breakdowns · down on 14 of 21 days 97.9%
18. 18The Flying Snoopy4h 7m lost · 6 breakdowns · down on 10 of 21 days 98.6%
19. 19Snoopy's Flying Ace Adventure3h 53m lost · 9 breakdowns · down on 10 of 21 days 98.6%
20. 20Mario Kart: Koopa's Challenge™3h 22m lost · 14 breakdowns · down on 21 of 21 days 98.6%
21. 21Yoshi's Adventure™2h 58m lost · 7 breakdowns · down on 13 of 21 days 98.7%
22. 22Hello Kitty's Cupcake Dream3h 21m lost · 3 breakdowns · down on 3 of 21 days 98.9%
23. 23Freeze Ray Sliders2h 9m lost · 3 breakdowns · down on 13 of 21 days 99.2%
24. 24Illumination’s Villain-Con Minion Blast8m lost · 0 breakdowns · down on 1 of 21 days 100%

Breakdowns cluster at 8pm, with 52 of the 230 closures that started before the park's final hour beginning then - so the ride you most want is safest earlier in the day, not saved for last. A further 34 rides simply were not running at opening, which is a late start rather than a fault and is counted separately. The other 123 closures start in the 9pm hour, when the park is shutting - those are rides finishing their day, not failing, so they are left out here.

The worst day in this window was 21 Oct, when 87.9% of the park's ride hours were lost and 49 of 56 rides went down at some point.