The Yellow and Blue fight in Deltarune Chapter 5 doesn’t end when you deal damage. It ends when you prove your case. Yellow drags Kris and the party into a trial on every other turn, and you only escape by naming the right culprit and backing it up with the right piece of evidence. Pick wrong, and the duo simply replays their last attack pattern until the next trial comes around, so guessing only stretches the fight out.
Quick answer: Solve the four cases in order with these pairs — Case 1: Seth + PerpBook, Case 2: Green + YellowShred, Case 3: Aqua + RedSplatter, Case 4: Blue + BlueString. Land the fourth correctly and the battle ends.
How to start a trial against Yellow and Blue
A trial only begins once you have enough TP to use the Justice ACT. Use Kris’ ACT, choose Yellow, and the trial option appears. Yellow then reads out the crime, and you select a suspect followed by the evidence that ties them to it.
If your TP is too low, spend turns on HelpOut with Susie and Ralsei to build it back up quickly. The Justice ACT needs roughly 40% TP to fire, so don’t try to open a trial until the gauge can cover it.
There’s a second snag. If you reach a case and the game tells you that you don’t feel you have enough evidence, you can’t run Justice yet. Use Kris’ ACT on Blue and pick Evidence instead. It costs around 20% TP, and Blue hands over the missing item so you can continue. For many players this hits right after the first two cases.
All four trial answers (culprit and evidence)
The cases run in a fixed order, and there are five suspects in play across the fight — Aqua, Seth, Green, Yellow, and Blue. Hints during the fight, such as a line about Green oiling the popcorn fan, point toward each answer, but you can skip the detective work and go straight to the correct pairs below.
| Case | Culprit | Evidence |
|---|---|---|
| 1. A Floradinn was crushed flat | Seth | PerpBook |
| 2. Yellow’s favorite shirt turned jet black | Green | YellowShred |
| 3. Green’s handkerchief was stolen | Aqua | RedSplatter |
| 4. Yellow’s secret special petals went missing | Blue | BlueString |
Case 1: The crushed Floradinn
The victim is a Floradinn that claims it was flattened. Seth is the culprit, and the PerpBook is the evidence, since Seth carries that book everywhere.
Case 2: Yellow’s vandalized shirt
Yellow is the victim here, reporting that his favorite yellow shirt was defaced and blacked out. Accuse Green and present the YellowShred, the torn piece of the shirt.
Case 3: Green’s stolen handkerchief
This is the case that usually forces an Evidence request from Blue first. Green reports the theft of his handkerchief. Aqua is the culprit, and the RedSplatter is the evidence, left behind while trying to change the handkerchief’s look.
Case 4: Yellow’s missing petals
Yellow returns as the victim, now saying his secret special petals are gone. The answer is Blue plus the BlueString. Yellow gets angry at the accusation, but Blue confesses. Yellow then tries to punish himself, only for the bullets in his revolver to come out as blue flowers, and he calls off the whole fight.
How you know the fight is over
Clearing the fourth case is the trigger. Once Blue is named with the BlueString and confesses, Yellow becomes shocked, a cutscene plays, and the battle ends. You’re then free to push deeper into the castle in the back half of the chapter.
If a case doesn’t resolve, it’s almost always one of two reasons. Either you picked the wrong culprit or wrong evidence, which loops the previous turn’s attack, or you didn’t have the right evidence on hand and need to pull it from Blue using the Evidence ACT before Justice will work.
Surviving the attacks between trials
This battle leans far more on the trials than on dodging, so don’t panic about taking hits. If a party member goes down, use Blue’s Integrity ACT to revive everyone at the cost of TP, and lean on Ralsei’s heal spell to top off health. Taking damage just makes the fight longer, not unwinnable.
- A blue-dotted line forms into a flower and fires bullet petals; weave between them as several flowers stack in the box.
- Flowers appear before firing, turning their petals into moving obstacles — same dodging approach as the first attack.
- Music notes scroll across while petals rain from top and bottom; slip between the wavy lines and watch the falling petals.
- Tiny ballerinas cross the bottom and jump on an every-other pattern; sit between two and shift your heart over the one about to leap.
Keep the Justice and Evidence ACTs in mind on every turn, build TP when you’re short, and the four answers above carry you through to Yellow’s surrender without a single wasted trial.
