Akumu

"Kumu... There you are..."

- Bete Noire after Akumu saved her from Gaster's attack

Akumu, or Kumu for short, is a part of Bete in the sense that Bete Noire spell can split itself into two different beings. Not much is known about it, but it is considered the secondary antagonist of Season 2 .

The creature is voiced by Strelok, who also voices Frisk and Flowey and provides the sound design.

Personality
"You're always hungry."

- Bete to Kumu, also showing Kumu's hunger for souls

Much like Betty, 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. 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 this creature. This was revealed in the description of a speedpaint video.

Appearance
"HE'S SO CUT- oh..."

- Camila in a post. Kumu is a bubblegum-like pink blob that has a face. It appears to be able to change its size and shape.

When it's in its HATE form, it gains black sclera and a black crooked mouth.

In Bete's true form, the pink matter inside of her is similar to Akumu.

Abilities

 * Shapeshifting: Kumu can change shape and turn into a wide variety of weapons, different objects and is able to change their form entirely. An example of this is in Dust when Asriel tried to attack Bete and he shielded her, whilst another example 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. Its strength is unknown but it is capable of cutting through 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.
 * Shield: As seen in Love Part 1 when Undyne hurled a spear at Bete and Kumu, Kumu became a shield to protect Bete.
 * 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. He was also able to destroy multiple souls at once that were contained inside of him in the beginning of My Promise.
 * HATE Corruption: Akumu was also shown in the beginning of My Promise to corrupt HATE on souls.
 * Spear of Fear: In Love Part 2, it was revealed that Akumu can summon Spear of Fear too. They used it to collect Asriel's soul.

My Sunshine
"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, likely about to act in defense. The creature soon shape-shifted into a tiny flower on her head after it had been calmed. Kumu stays on Bete's head as a tiny pink flower for the rest of the episode.

Dust
When Frisk comes over to Gaster's house, Kumu can be seen flying around, playfully carrying 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.

Do or Die
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, which causes Bete Noire to realize that she has enough magic to "start her plan" (which is the soul harvest).

Before fighting Gaster, Bete is seen ordering Kumu to attack Alphys before one of her pink blobs attacked her. Later, Kumu fights alongside Bete Noire against Gaster. 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 enters the room. Bete then tricks her into killing Alphys and attempts to kill her too. But before she can, Undyne turns into her into Undyne The Undying form. The episode ends at this point.

Love Part 1
Near the beginning of the episode, Kumu and Bete fight Undyne the Undying, who easily overwhelms 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 eats the Hate vial they took from Jessica in Dust, allowing for Bete to recover half of their body using Hate, but even then, this was still not enough to defeat Undyne.

This was especially since Bete was seen to be losing control due to the hate, and even coughed some of it, which caused both of them to flee from the 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, and goes through some long dialogue before summoning the Pink Creature(s)Kumu proceeds to consume the creatures along with 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.

Love Part 2
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, but before the duo could finish them, Asriel decided to interfere. However, Kumu managed to take his soul while he was fighting her, and 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, 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.

My Promise
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 them and she needed to ensure she had the hate at bay. Bete then 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.

Trivia

 * ￼Akumu is written 悪夢 in terms of Kanji which means nightmare in Japanese.
 * In addition, "Akuma" (悪魔) translated to English means Evil/Devil/Demon.
 * 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 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 one Tumblr post, Camila released a canon conversation between Bete and Akumu that was never alluded to in the series.
 * HATE is unable to control Kumu because of an unknown reason.
 * Kumu and Bete were completely overwhelmed by Undyne's enormous strength and couldn'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.
 * At the end of My Sunshine, the sleeping "Bete" at Gaster's house is actually Akumu disguised as her

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