Oshi no Ko has quickly risen to the top of various anime lists thanks to its superb premiere episode that blended elements of isekai, murder-mystery and fantasy into a fascinating look at the Japanese idol industry. The anime's opening and ending have likewise created a stir in viewers for their gorgeous visuals and addicting beats, with "Idol" garnering 10 million views and "Mephisto" seeing 4.8 million views in just two weeks.

Both "Idol" and "Mephisto" highlight the different paths Aqua and Ruby will take. YOASOBI's "Idol" focuses heavily on Ai Hoshino's story, the dark side of the idol industry, and how it has consequently affected her children's decisions after she was killed. Queen Bee's "Mephisto" highlights how Aqua's choice to avenge two ghosts -- Ai's and his own -- takes him further and further away from his sister Ruby.

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Oshi no Ko's Opening Theme "Idol" Represents Ai's Rise and Fall

Ai Hoshino performing as an idol on stage in Oshi no Ko

Oshi no Ko's creator Aka Akasaka recently published the short story "45510", which served as the inspiration to "Idol." Written from the perspective of either a fan or another member of B-Komachi, the narrator admits she's jealous of Ai for being that "perfect and ultimate idol," simultaneously chiding her to not show "a heart that you don't want to know." It's only by showing this false side of herself that it "makes a real Ai," which is in line with Ai's belief: lies are her way of expressing her love.

"Idol" combines pop with a gothic rendition of what sounds like a church chant. There's an almost cruel sharpness to the song that is muffled by how bright and poppy it sounds, similar to the harsh realities of the idol industry and how Ai lived: she always had to wear a mask that would appeal to the masses. She had gone so far as to convince herself that one day this mask would become real.

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The animation accompanying "Idol" has Ai's twin children appear on a stage. But while Ruby shoots a quick smile at the camera, Aqua chooses to walk away, representing his desire to distance himself from fame. Compared to his sister, Aqua is constantly shrouded in darkness. The scene with Aqua in his first life before transitioning into his second one is interesting. Dr. Gorou stands in a crowd as a few light sticks wave around him, but as soon as it changes to Aqua, the screen is filled from top to bottom with light sticks.

Gorou was part of the background and only had a small idea of what Ai went through as an idol, but as Aqua he's firmly in the spotlight and has a better understanding of her experience. Despite many people being around him and expressing their love toward him, he still feels lonely. The shattering glass as Aqua crashes through with a desperate expression seems to suggest his efforts to find his mother's killer and protect his sister may be fruitless.

Despite the circumstances of her mother's death, Ruby wants to embrace the life Ai has left behind as shown by her reaching up to the skies as a star drifts down. The brief flash of Sarina Oshi no Ko's opening acts as a reminder to Ruby: she wasn't able to realize her dreams in that life, but she can do it now. Ruby wants to move on and press forward with her life.

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Oshi no Ko's Ending Theme "Mephisto" Shows Aqua's Dark State of Mind

Aqua and Ruby are ready for school in Oshi no Ko.

Oshi no Ko's ending theme has the curtain open as a rabbit wearing a dress twirls around, giving the performance of her lifetime. As she spins, the red threads that suspend her wrap around her body. The rabbit bows and then violently explodes, throwing the entire scene into darkness with glass shards showering her still form.

It's an ominous start that fits the somber edge of "Mephisto". Ai is represented by the rabbit and the red strings -- likely referencing the red strings of fate -- are tied to various parts of her body. As soon as she moves and starts performing for the audience, they constrict her until it becomes too much and she explodes. The red strings of fate are consequently transferred to Aqua, as shown when he arrives at the bottom of the steps to bodies strewn around, to symbolize how his and Ai's fates are tied. His hunger for revenge will drown him if he's not careful. By the time he realizes he wants a different life, as depicted by him trying to grab Ruby's hand, it may prove to be too late.

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Oshi no Ko's ED highlights Aqua's descent into darkness as shown by him walking down the stairs, face hidden by his hood and his right eye shrouded in darkness save for the star. What's fueling him are his memories with Ai and Ruby, yet despite how happy he was when he was with them, it's dim, showing how grief-stricken he is. Ruby, however, has an assured and confident aura as she walks up the stairs, symbolizing her decision to reach achieve her dreams of becoming an idol. She remembers her past life as Sarina when she was sick in the hospital, but there's a softness to her memories; this is shown when the camera focuses on her beanie with the bunny decoration, symbolizing Ai, rather than what her illness took from her. She's focused on her goal to follow her mother's footsteps rather than her pain in the past.

The title "Mephisto" refers to Mephistopheles, the demon in Doctor Faustus to whom the eponymous character sells his soul. The name has a number of meanings, including "not loving light", and refers to vapors that can destroy human life. In Aqua's quest to avenge Ai's death, he has basically sold his soul to the demon, symbolized by the star in his eye turning black and the lyrics where it says "I'll risk my life, give up my life." Aqua is single-minded in his goal in Oshi no Ko. "Mephisto" could also be a warning in that if he's not careful in his pursuit, he may end up hurting the very people he's trying to protect.