|“||Kumu... There you are...||„|
|~ Bete Noire after Akumu saved her from Gaster's attack|
|“||You're always hungry.||„|
|~ Bete to Kumu, also showing Kumu's hunger for souls|
Much like Bete Noire, throughout My Sunshine and a portion of Dust, Kumu didn't seem to be evil. It acted somewhat friendly and playful, which was shown when it ran off with one of Gaster's books, which is suspected to be the tale of the twin siblings. However, according to Bete, it was a tad overprotective. But this all changed after the creature revealed the evil inside itself.
Kumu appears to be sadistic and doesn't care if it severely hurts others. According to a post, the creature wields a hunger for souls and treasures Bete as their best and only friend.
Not much else is know about Kumu's personality, apart from the fact that Bete Noire is controlling the creature. This was revealed in the description of a speedpaint video.
|“||He's so cut- oh...||„|
|~ Camila in a post.|
Kumu is a bubblegum pink blob that has a face. It appears to be able to change its size and shape.
When in its HATE form it gains black sclera and a black crooked mouth.
- Shapeshifting: Kumu can change shape and turn into a wide variety of weapons, different objects and be able to change their form entirely. An example of this is in Dust when Asriel tried to attack Bete. An example of being able to change form is when it was able to change into a mini version of Bete.
- Sickle: Kumu transformed into what appears to be a sickle-like object in Love Part 1 in an attempt to try to fight off Undyne the Undying. It's strength is unknown but it was capable of cutting skin.
- Arm-mounted blades: Kumu can mount itself onto one of Bete's arms to create an arm-mounted blade, which was displayed in Do or Die.
- Shields: As seen in Love Part 1 when Undyne hurled a spear at Bete and Kumu.
- Flight/Floating: Kumu has shown the ability of flight very frequently throughout the series.
- Summoning: In Do or Die, Kumu summoned several pink creatures for the soul harvest.
- Pocket Reality Manipulation: Both the Pink creatures and Akumu have a reality pocket to contains the souls and only they can show them.
- Spear of Fear: In Love Part 2, it was revealed that Akumu can summon it too, they used it to collect Asriel's soul.
|“||What is that thing? It's awesome.||„|
|~ Frisk complimenting Kumu|
|“||Don't come out! Stay there!||„|
|~ Bete to Kumu|
After Frisk took Jessica Grey and Bete to Toriel's school, when Bete was meeting Toriel, her soul reacted to Toriel's approach. As a result, Kumu popped out of Bete. The creature soon shapeshifted into a tiny flower on her head. Kumu stays on Bete's head as a tiny pink flower for the rest of the episode.
When Frisk comes over to Gaster's house, Kumu can be seen playfully carrying around a book.
Near the end of the episode, Asriel and Sans find out about Bete Noire's true intentions. Before leaving, Bete soon appears. She gave up on attempting to hide the monster inside her and removes Sans's soul from his body and feeds Kumu with it.
Asriel soon escapes and Bete asks Jessica for the HATE vial that she has. After refusing to give it to her, Kumu grabs Jessica and slams her against the wall. The screen soon cuts to black.
Minutes into the animation, Kumu is seen with Bete at the Core. The creature soon shows Bete Sans' soul and how it was draining its magic. Bete Noire soon realizes that she had enough magic to "start her plan" (which is the soul harvest).
During the fight, Bete stabs Gaster in the back, causing him to pass out. But thankfully, Jessica and Alphys come in just in time to rescue him. Alphys gives Jessica a dark blue artifact, which allows her to teleport back home. Alphys puts up a green shield around herself and activates the nullifier. The nullifier then attacked Bete and Kumu.
Alphys' shield soon gets deactivated. Bete then attacks her. It turns out that it didn't affect either of them because it only works on monsters and humans but she and Kumu are neither of the two. Undyne soon entered the room. Bete then tricks her into killing Alphys and attempted to kill her too. But she turned into Undyne The Undying. The episode ended at this point.
Near the beginning of the episode, Kumu and Bete fight Undyne the Undying, who easily overwhelmed the two with her Determination. Undyne then uses her special attack, "The Spear of Justice". That attack was enough to disintegrate half of Bete Noire's body and destroy the roof of the entire nullifier room. Akumu then ate the Hate vial they took from Jessica in Dust. Bete was able to recover half of their body using Hate. But this was still not enough to defeat Undyne. Bete then coughed out some Hate, not knowing what may happen to Bete both of them flee from battle.
Later, Bete and Kumu are seen hiding out in an abandoned shed. Bete confronted Akumu as she told the creature that she hardly felt like herself now due to the HATE. Eventually, Bete's pink blobs arrive. Kumu proceeds to consume them, and the souls they managed to gather.
Neither Bete nor Kumu was seen throughout the rest of the episode, not counting when Frisk mentioned them when they were talking to Asriel.
When the episode began, Kumu was seen with Bete in an image inside Frisk's mind.
Later, the duo encountered Frisk and they began to fight. Before the duo could finish them, Asriel decided to interfere. However, Kumu managed to take his soul while he was fighting her. Upon seeing Asriel's "death", Frisk's LV became 19 and turned the tides of the battle as a result, creating a fair battle.
Getting an idea, Bete used Kumu to grab Sans' soul and fill it with HATE. Sans, now under HATE's control, began to fight Frisk. After Papyrus jumped in the fight and managed to remove the HATE from Sans, Bete and Kumu were forced to retreat.
Akumu was seen at the beginning of the episode, with Bete, who was furious that they were running away even though they were supposed to be feared. Bete orders Akumu to show them the souls that were infected by HATE, Akumu then shows Bete the souls they had consumed by making itself bigger and making a force field around Bete. Bete then starts cracking the souls due to the fact that HATE has infected most of the souls. Bete decides to keep Asriel's soul and absorb the magic of Cam's soul then tells Akumu to destroy the remaining souls.
Bete tells Akumu that she is tired of being split in two so she throws her spear at Akumu in order to fuse with them. The spear hits Bete and then slowly both Bete and Akumu start fusing transforming into their true form. Akumu was not seen again as they were fused with Bete for the rest of the episode.
- Before his revival, Camila revealed that Sans' soul was still alive inside Kumu.
- If Akumu dies, Bete will slowly die in a short time and vice versa. They don't die immediately, it should take a while. This could be because they share the same soul.
- Akumu doesn't have a gender, just like Bete.However, unlike Bete, the creature is typically referred to as an asexual being but is referred to as a "he" by Camila.
- It is possible to remove a soul from Akumu.
- In Japanese, Akumu means "Nightmare" and Akuma means "Demon".
- In one Tumblr post, Camila released a canon conversation between Bete and Akumu that was never alluded to in-series. 
- HATE is unable to control Kumu because of an unknown reason.
- Kumu and Bete were completely overwhelmed by Undyne and can't take her down.
- Kumu and Bete were looking for a "very special" soul in the core.
- Killing half of humans and monsters is enough to stop Kumu and Bete.
- In Undyne's battle with Bete, Akumu shielded Bete from Undyne. Before the episode came out, Akumu as a shield was seen as impenetrable, however, Undyne easily cut through Akumu with her spear; proving Undyne's great strength.
- On her amino, Camila released a GIF of Kumu and Bete before she finished Do or Die.
- At the end of My Sunshine, the sleeping "Bete" at Gaster's house was Akumu disguised as her. 
- ↑ Not much else is know about Kumu's personality, apart from the fact that Bete is controlling the creature. This was revealed in the description of a speedpaint video. (Link)
- ↑ Before his revival, Camila revealed that Sans' soul was still alive inside Kumu. (Link)
- ↑ Akumu doesn't have gender like Bete. However, unlike Bete, the creature is typically referred to as an asexual being but is referred to as a "he" by Camila. (Link).
- ↑ It is possible to remove a soul from Akumu. (Link)
- ↑ In one Tumblr post, Camila released a canon conversation about Bete. A conversation that was never in the series. Bete talking with Kumu, about her goals of killing everyone. (Link)
- ↑ HATE cannot control Kumu because of an unknown reason. (Link)
- ↑ Kumu and Bete were completely overwhelmed by Undyne and can't take her down. (Link)
- ↑ Kumu and Bete were looking for a "very special" soul in the core. (Link 1)
- ↑ Kumu and Bete were looking for a "very special" soul in the core. (Link 2)
- ↑ Killing half of humans and monsters is enough to stop Kumu and Bete. (Link)
- ↑ At the end of My Sunshine, the "Bete" at Gaster's house was Akumu disguised as her (Link)
|Villains||HATE ♡ Chara ♡ Agate Lightvale ♡ Bête Noire ♡|
|Main Characters||Frisk ♡ Gaster ♡ Sans ♡ Flowey ♡/Asriel ♡ Undyne ♡ Papyrus ♡ Toriel ♡ Asgore ♡ Alphys ♡ Mettaton ♡|
|Side Characters||Jessica ♡ Amber Lightvale ♡ Cam ♡ Lily ♡ Robin ♡ Abigail ♡ Seth ♡ Zachary ♡ Hugo ♡ Ronan Cass ♡ Rave Rutrow ♡ Isabelle ♡|
|Background Characters||Temmie ♡ Burgerpants ♡ Jerry ♡ Grillby ♡ Muffet ♡ Amalgamates ♡ Alina ♡ Noah ♡ Akumu/Pink Creature(s)/Pink Giant ♡|
|The Seven Wizards||Copper Lightvale ♡ Agate Lightvale ♡ Roy Goldburn ♡ Shane Goldburn ♡ Mila Rutrow ♡ Kody Fallenfire ♡ Rin Winterway ♡|