How to get the Mystery Key and defeat the secret boss in Deltarune Chapter 5

The Dark World holds plenty of secrets in Deltarune, and there’s a new secret boss to defeat in Chapter 5. Named Pink, you’ll encounter her in the Flower Castle after reaching the top. Defeating her will not be easy, but it is doable. Table of contentsHow to get the Mystery Key in Deltarune Chapter 5How to summon Pink in Deltarune Chapter 5How to defeat Pink (secret boss) in Deltarune Chapter 5 How to get the Mystery Key in Deltarune Chapter 5https://embeds.beehiiv.com/a8d62108-86ed-4039-bf49-44877ba62c15 To summon Pink, you’ll need to reach the Pink Door located inside the castle. However, you’ll find that the door is locked. To gain access, you’ll need a Mystery Key. Screenshot by Destructoid You can purchase the Mystery Key from the shop in the Cliffs. If you have unlocked the magic door that allows us to fast travel, just select the location directly. Screenshot by Destructoid To get the Mystery Key, you’ll need to get 10 Pink Coins. This currency is spread all over the Dark World, and there are reportedly 19 of them to find. I have found 18 of them, but you require just 10. There’s no extra benefits from getting more, since they don’t seem to have any other use. If you’re wondering where the Pink Door is, use the Pink Coin guide I have linked above, and follow instructions for the 18th coin. Simply head to the Pink Door, and you can then use the key to unlock. How to summon Pink in Deltarune Chapter 5 Once you head inside from the Pink Door, you’ll meet…Orange (not Pink). Orange will be once again do the usual antics, but then arrives Pink. She asks why are you guys picking on her sibling. This follows a conversation, and I for a moment thought that there’s no fight. Things appeared to be solving pretty amicably until Susie said something that shouldn’t. Screenshot by Destructoid This officially will start the secret boss fight. Orange won’t take any part in the battle, but defeating Pink is no mean task. Incidentally, Pink is none other than Mad Mew Mew from the Undertale series. How to defeat Pink (secret boss) in Deltarune Chapter 5 Screenshot by Destructoid The fight will last for several rounds. First, forget attacking her since you can’t do any damage the traditional route. If you observe the right side of the image above, you’ll notice the Doki Meter. Your aim is to fill the meter as quickly as you can. Screenshot by Destructoid So how do you fill it up? Go to the Act section for Kris and Susie, and you’ll get the option to Flirt (there are more options like MegaFlirt, but they require more TP). Flirting with Pink will fill up her Doki Meter. With Ralsei, you’ll first want to increase the max TP capacity first so that you can use the advanced Flirt moves for more impact. How do you get TP? For this fight, you’ll need to wait for Pink to attack. When she attacks, it will usually involve box puzzles. You’ll have to control your heart and avoid the incoming threats. Occasionally, it can be onrushing cat-emoji trains that do damage on impact. Sometimes, there will be explosions. Screenshot by Destructoid Not only do you need to avoid taking damage, but you also have to look out for pink hearts. These hearts appear routinely, and they give you TP. The more pink hearts you get, the more TP you have at the start of your turn. Just reach the Pink Hearts by moving your heart with the LS button. Screenshot by Destructoid When the meter fills up, Pink will start ‘dating’ you (yes, there’s no typo in that). To please her, choose answers that affirm her questions until you run out of suitable options. Screenshot by Destructoid During the second round, you’ll need to repeat the steps mentioned above until another date begins. This time, however, you’ll find that Pink is acting in a bipolar behavior. As you answer her questions, she will reach a splitting point where she will turn into two persons. This happens as her body and ghost splits. The duo also prefers exactly opposite things, which makes your life harder. Screenshot by Destructoid The third round is where things change. For starters, you’ll need to now get 20 Doki, so it takes longer to fill. The box puzzles also get more complex; you’ll gain more Pink Hearts, but also take more damage if your heart gets trapped. Screenshot by Destructoid The date phase for the third round is really chaotic. As her ghost merges with her, Pink loses control and loses her mind. You’ll have to gain the Pink Hearts from the puzzles while avoiding the “Die” words, as they will reset your progress. The final piece of puzzle makes you run to the end while you avoid the “Die” word. Screenshot by Destructoid The final round is even stranger, as the Doki Meter will fill on its own. However, you’ll need to survive a few turns of incoming attacks as the meter fills all the way up to 20. Screenshot by Destructoid The final date is beautiful as you answer as Pink’s ghost. While the body wants to know what went wrong, you reply (choose the correct answers

Jun 27, 2026 - 02:20

How to get the Mystery Key and defeat the secret boss in Deltarune Chapter 5

The Dark World holds plenty of secrets in Deltarune, and there’s a new secret boss to defeat in Chapter 5. Named Pink, you’ll encounter her in the Flower Castle after reaching the top. Defeating her will not be easy, but it is doable.

Table of contents

How to get the Mystery Key in Deltarune Chapter 5

https://embeds.beehiiv.com/a8d62108-86ed-4039-bf49-44877ba62c15 To summon Pink, you’ll need to reach the Pink Door located inside the castle. However, you’ll find that the door is locked. To gain access, you’ll need a Mystery Key.

Screenshot by Destructoid You can purchase the Mystery Key from the shop in the Cliffs. If you have unlocked the magic door that allows us to fast travel, just select the location directly.

Screenshot by Destructoid To get the Mystery Key, you’ll need to get 10 Pink Coins. This currency is spread all over the Dark World, and there are reportedly 19 of them to find. I have found 18 of them, but you require just 10. There’s no extra benefits from getting more, since they don’t seem to have any other use. If you’re wondering where the Pink Door is, use the Pink Coin guide I have linked above, and follow instructions for the 18th coin.

Simply head to the Pink Door, and you can then use the key to unlock.

How to summon Pink in Deltarune Chapter 5

Once you head inside from the Pink Door, you’ll meet…Orange (not Pink). Orange will be once again do the usual antics, but then arrives Pink. She asks why are you guys picking on her sibling. This follows a conversation, and I for a moment thought that there’s no fight. Things appeared to be solving pretty amicably until Susie said something that shouldn’t.

Screenshot by Destructoid This officially will start the secret boss fight. Orange won’t take any part in the battle, but defeating Pink is no mean task. Incidentally, Pink is none other than Mad Mew Mew from the Undertale series.

How to defeat Pink (secret boss) in Deltarune Chapter 5

Screenshot by Destructoid The fight will last for several rounds. First, forget attacking her since you can’t do any damage the traditional route. If you observe the right side of the image above, you’ll notice the Doki Meter. Your aim is to fill the meter as quickly as you can.

Screenshot by Destructoid So how do you fill it up? Go to the Act section for Kris and Susie, and you’ll get the option to Flirt (there are more options like MegaFlirt, but they require more TP). Flirting with Pink will fill up her Doki Meter. With Ralsei, you’ll first want to increase the max TP capacity first so that you can use the advanced Flirt moves for more impact.

How do you get TP? For this fight, you’ll need to wait for Pink to attack. When she attacks, it will usually involve box puzzles. You’ll have to control your heart and avoid the incoming threats. Occasionally, it can be onrushing cat-emoji trains that do damage on impact. Sometimes, there will be explosions.

Screenshot by Destructoid Not only do you need to avoid taking damage, but you also have to look out for pink hearts. These hearts appear routinely, and they give you TP. The more pink hearts you get, the more TP you have at the start of your turn. Just reach the Pink Hearts by moving your heart with the LS button.

Screenshot by Destructoid When the meter fills up, Pink will start ‘dating’ you (yes, there’s no typo in that). To please her, choose answers that affirm her questions until you run out of suitable options.

Screenshot by Destructoid During the second round, you’ll need to repeat the steps mentioned above until another date begins. This time, however, you’ll find that Pink is acting in a bipolar behavior. As you answer her questions, she will reach a splitting point where she will turn into two persons. This happens as her body and ghost splits. The duo also prefers exactly opposite things, which makes your life harder.

Screenshot by Destructoid The third round is where things change. For starters, you’ll need to now get 20 Doki, so it takes longer to fill. The box puzzles also get more complex; you’ll gain more Pink Hearts, but also take more damage if your heart gets trapped.

Screenshot by Destructoid The date phase for the third round is really chaotic. As her ghost merges with her, Pink loses control and loses her mind. You’ll have to gain the Pink Hearts from the puzzles while avoiding the “Die” words, as they will reset your progress. The final piece of puzzle makes you run to the end while you avoid the “Die” word.

Screenshot by Destructoid The final round is even stranger, as the Doki Meter will fill on its own. However, you’ll need to survive a few turns of incoming attacks as the meter fills all the way up to 20.

Screenshot by Destructoid The final date is beautiful as you answer as Pink’s ghost. While the body wants to know what went wrong, you reply (choose the correct answers) that you didn’t like how Kris and company appreciated you. She felt that she will lose Pink, but now she understands that to be happy, she will have to accept both their wishes.

Screenshot by Destructoid This ends the fight, and she thanks you for helping her out. As a reward, you get the Shadow Crystal and something truly special (won’t spoil it for you).

0 The post How to get the Mystery Key and defeat the secret boss in Deltarune Chapter 5 appeared first on Destructoid.

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