There's something to be said about the very nature of anime in comparison to any other form of entertainment. Anime can be more contemplative and serene than any other type of show, taking time to delve into the surroundings of their characters and where they live as well as thoroughly exploring a character's inner thoughts and feelings. On the other hand though, anime can also be more bombastic and over the top than some people would like. However, for those who enjoy the high octane energy that anime can bring, there's nothing better than when a show opens with a theme song that gets the blood boiling.
The right song intro to an anime can really get a viewer into the right state of mind. They can also help to reflect the personality of the production as a whole and give those who have never seen the show a better idea of what they can expect. One thing that's also a lot of fun about these intros is that they sometimes will serve the function of a music video that depicts events that are similar, but not exactly like the actual events that transpire in the series. It's sort of like the openings to Rick and Morty each season except less ridiculous and also with an underlying layer of great music underneath. While these songs rarely stay as the only opening song for a series and will change from season to season (or sometimes even within the same season), these are some of the very best that have burned themselves into viewer's memories.
"Rewrite," by Asian Kung Fu Generation (Fullmetal Alchemist)
While many fans of the Elric brothers have grown more fond of the recent Fullmetal Alchemist: Brotherhood, the original series still had its share of incredible theme song openings. In particular, the song 'Rewrite,' by Asian Kung Fu Generation is easily the very best. The song fits the opening animation perfectly, introducing a chord progression that keeps the kinetic energy of what's seen on-screen high and continuing to build as it goes.
This wall of noise appears to be a bit lower in energy compared to other anime openings, but just as the viewer begins to suspect this the song pulls the rug out from beneath them and kicks into an emotionally resonant chorus. Everything is amped up, becoming faster and even more emotionally cathartic as the animation in the background suddenly switches to particularly intense scenes of action. This is a textbook example of how to concoct a great anime intro, with plenty of emotion, vibes, and perfectly matched animation.
"Serment," by Kawada Mami (Shakugan No Shana)
For those unfamiliar with Shakugan No Shana, it's sort of like a Shonen story with a heavy does of female empowerment and decidedly Shojo/romantic stylings. The story follows Sakai Yuji who meets a flame haired girl named Shana who fights monsters that feed on the existence of humans and erase them from the world. Once a person is erased, they are replaced by a version of themselves known as a Torch (due to the blue flames inside them, their remaining "existence"). Torches are meant to slowly fade away so as not to heavily disrupt the balance of the world and having people immediately notice when others are erased.
The theme songs of Shakugan No Shana are the best part of the series. This opening in particular for season 2 is especially heavy, and unapologetically comes out of the gate singing with riffs soaked in heavy distortion. The action behind the song does a solid job of incorporating musical beats into animated transitions and the flame theme of the show allows for some really eye-catching flourishes. Even if the whole series doesn't strike someone's fancy, the theme songs are definitely worth a listen.
"Pokémon Theme Song," performed by Jason Paige (Pokémon)
Look, occasionally there are moments captured within recording studios that will change the very course of the future as people know it. The Pokémon theme song is one of those songs. Not only is the song literally about becoming a Pokémon master, but it just resonates with the viewer's heartstrings and has resulted in many a screaming sing-along among groups of friendly nerds.
Keep in mind that this also came out alongside the original games and Pokémon cards. This theme song was the very first time that many 90's children had ever seen a Pokémon fully animated and depicted within this world. It was a hell of an introduction then and it's one that has not lost any of its catchiness decades later. If anything, the show could return to using the original theme song and fans would probably be delighted.
"Twister," by Takeharu Ishimoto (The World Ends With You: The Animation)
The world was originally supposed to receive a song called "Teenage City Riot," prior to a bank fraud scandal in Japan leading the show to pull the song entirely and opt instead to use "Twister." Technically this song actually got its start with the DS original version of the The World End With You. The song is just as unique and catchy as ever though, with a mixture of sounds that reflects the many eclectic influences of Shibuya. There's an acoustic guitar line playing underneath, some horns, and a hip hop beat with vocals that will have you singing along to its nonsensical lyrics.