I have verified that Nagisa's 2:31.942 used Rapid Fire (wheelie input every other frame). It's also clear from the ghost viewer if you watch it frame by frame:
http://www.ninrankings.org/ghostdatabase/ghostviewer.php?id=14682Since the input viewer has some bugs, it's important to verify the inputs by looking at the inputs in the decoded ghost file. Myself and others have checked that and verified it's Rapid Fire, example:
https://twitter.com/MKRFirestone/status/1188909429699121152His WRs after that show no signs of cheating. Back in 2012, myself and Maschell caught cheaters using a mix of automated and manual checking. For example, Nooboss was caught from Maschell's automated checker, and some others like Jay were caught by me manually checking ghosts. For Nagisa I definitley checked some of his ghosts and found no signs of cheating. Unfortunately, I only checked his more recent times and missed this 2:31.942 run from 2010. I checked ghosts for pretty much all the top players from that era but mainly just checked a sample of their best times.
There hasn't been a mass automated check of the database with all the techniques we know about. The new technique of checking if GCN ghosts have impossible control stick inputs is creative, but I think the traditional live replay check would catch most of those anyways (checking if any 2 ghosts share the same starting inputs, which was used to catch people like Malleo). I guess the only new case it catches is when a GCN player copied a Nunchuck/Wheel ghost when we don't have the Nunchuck/Wheel ghost available.
I ran an automated check for live replay on a bunch of the GV2 ghosts a few years ago but didn't find anything new. I thought about running automated checks on the entire database (including for rapid fire) but decided not to spend time doing that, since I didn't really expect much to come out of that. I guess that would have caught Nagisa, who unfortunately slipped through the cracks and was able to set "WRs" as late as 2015 without people knowing about this cheated 2010 run. It's nice that there are other people who are looking at the ghost inputs and discovering new things (apparently it was Star who caught Nagisa).
Anyways, all of Nagisa's times have been deleted from mkwrs. The cheated run was his 2nd WR, done in May 2010. Obviously we can not trust any times done after that, even though they show no signs of cheating. It's possible he switched to an undetectable cheating method, like Mander did.
For his 1st WR (TF 1:51.547 on 2009-08-30), it's likely that run wasn't cheated since the wheelie rapid fire code wasn't public yet. However, there were other cheat codes that were public at that time, and we don't have the ghost available to check. So I think it's better to remove this time as well.
New times that have been added as a result of Nagisa's times being deleted:
2010-08-11: rDS 2'05"523 by Sword - 42"111 42"068 41"344 -
https://youtube.com/watch?v=AOh7YStEbhA2015-05-16: rDS 2'04"942 by Totom - 41"828 41"813 41"301 -
https://youtube.com/watch?v=oRZnmZg28Mk2013-07-22: rBC 2'31"507 by Rusox - 50"547 50"413 50"547 -
https://youtube.com/watch?v=YdbTLB0D1fwThere still might be more to add.
The backup of the deleted times, for reference:
Code:1472,"Nagisa","G1☆なぎさ","Japan","2009-08-30","Toad's Factory",111547,"Funky Kong","Bowser Bike","http://www.youtube.com/watch?v=WmGgZeD8q6E",0,0,4,0,-1,"GC","37.374","37.217","36.956","?-?-?","","",0
1667,"Nagisa","なぎさ","Japan","2010-05-24","N64 Bowser's Castle",151942,"Funky Kong","Bowser Bike","http://www.youtube.com/watch?v=O0v07HpV3oQ",105,0,32,0,-1,"GC","50.727","50.656","50.559","?-?-?","","http://www.ninrankings.org/ghostdatabase/ghostviewer.php?id=14682",0
1719,"Nagisa","fs なぎさ","Japan","2010-09-16","N64 Bowser's Castle",151857,"Funky Kong","Bowser Bike","http://www.youtube.com/watch?v=X6lIAphEvf4",1,0,32,0,-1,"GC","50.733","50.578","50.546","?-?-?","","http://www.ninrankings.org/ghostdatabase/ghostviewer.php?id=60015",0
1729,"Nagisa","fs なぎさ","Japan","2010-10-17","DS Delfino Square",125502,"Funky Kong","Bowser Bike","http://www.youtube.com/watch?v=CsPn0cHeCEg",27,0,23,0,-1,"GC","42.250","41.981","41.271","?-?-?","","http://www.ninrankings.org/ghostdatabase/ghostviewer.php?id=56872",0
2096,"Nagisa","なぎさ","Japan","2012-11-05","N64 Bowser's Castle",151621,"Funky Kong","Bowser Bike","http://www.youtube.com/watch?v=PCtUMk1E86A",217,0,32,0,-1,"GC","50.714","50.447","50.460","?-?-?","","http://www.ninrankings.org/ghostdatabase/ghostviewer.php?id=21232",0
2148,"Nagisa","なぎさ","Japan","2013-06-10","N64 Bowser's Castle",151604,"Funky Kong","Bowser Bike","http://www.youtube.com/watch?v=VQLreVOqXrg",8,0,32,0,-1,"GC","50.532","50.363","50.709","?-?-?","","http://www.ninrankings.org/ghostdatabase/ghostviewer.php?id=22921",0
2151,"Nagisa","なぎさ","Japan","2013-06-18","N64 Bowser's Castle",151580,"Funky Kong","Bowser Bike","N/A",0,0,32,0,-1,"GC","","","","?-?-?","","",0
2152,"Nagisa","なぎさ","Japan","2013-06-18","N64 Bowser's Castle",151492,"Funky Kong","Bowser Bike","http://www.youtube.com/watch?v=7B4K9gJxnp0",44,0,32,0,-1,"GC","50.589","50.475","50.428","?-?-?","","http://www.ninrankings.org/ghostdatabase/ghostviewer.php?id=24231",0
2285,"Nagisa","ターミナルパニック","Japan","2014-10-02","Bowser's Castle",141313,"Funky Kong","Bowser Bike","http://www.youtube.com/watch?v=Bb2AocM-AfQ",242,0,15,3,-1,"GC","47.148","47.186","46.979","?-?-?","","",0
2324,"Nagisa","Player","Japan","2015-04-29","DS Delfino Square",124909,"Funky Kong","Bowser Bike","http://www.youtube.com/watch?v=XgRt-pq0BmA",18,0,23,0,-1,"GC","41.930","41.848","41.131","?-?-?","","",0