Shakugan no Shana follows an age-old conflict between the human world and the Crimson Realm (紅世, Guze), which is a parallel universe to it.

It is the duty of Flame Hazes (フレイムヘイズ, Fureimu Heizu), humans who have contracted with a Crimson Lord, to maintain this balance by killing Denizens who disrupt it.

One such spell is the Seal (封絶, Fūzetsu), which creates a space where the Crimson Realm and the human world intersect and causalities, including time, are stopped.

It begins when high school student Yuji Sakai enters the conflict after a Flame Haze tells him that he died some time ago and that he is a Torch (トーチ, Tōchi), a human with greatly diminished Power of Existence which will eventually run out.

The organization is led by Hecate, Sydonay, and Bel Peol, three Lords collectively known as the Trinity who serve under the Snake of the Festival (祭礼の蛇, Sairei no Hebi), a God who resides within the Reiji Maigo.

When the Snake emerges, it merges its consciousness with Yuji's, taking command of Bal Masqué and planning to create a parallel world called Xanadu, which will serve as a paradise for Denizens with unlimited Power of Existence.

Yuji intends to go to Xanadu alone and ensure that humans and Denizens can learn to coexist, but Shana refuses to be left behind.

With the help of another spell from Lamia, Yuji restores all humans in Misaki City whose existence the Denizens absorbed before he and Shana depart for Xanadu together.

[3] Shortly before writing Shakugan no Shana, Takahashi made his debut as an author with A/B Extreme, which was awarded an honorable mention in the eighth Dengeki Novel Prize by MediaWorks (now ASCII Media Works) in 2001.

[2] Shakugan no Shana began as a light novel series written by Yashichiro Takahashi, with illustrations drawn by Noizi Ito.

[23][24] A special limited edition version of volume two was bundled with a booklet titled Grimoire including contributions from guest artists and writers for various illustrations, manga, and short stories.

[28] The manga is also licensed in South Korea by Daewon C.I.,[29] in Taiwan and Hong Kong by Kadokawa Media,[30] and in Germany by Egmont.

[31] A second manga illustrated by Shii Kiya, titled Shakugan no Shana X Eternal song: Harukanaru Uta (灼眼のシャナX Eternal song -遙かなる歌-), is based on the events of the tenth novel and began serialization in ASCII Media Works' manga magazine Dengeki Black Maoh on September 19, 2007.

[38] A 24-episode anime television series adaptation of Shakugan no Shana aired in Japan between October 6, 2005 and March 23, 2006 on TV Kanagawa.

[47] The film was released on DVD in Japan on September 21, 2007 in regular and special editions, which featured the full length 90-minute director's cut version.

[56][57][58] The 24-episode third season, titled Shakugan no Shana Final (灼眼のシャナIII -Final-),[59][60] aired between October 8, 2011 and March 24, 2012 on Tokyo MX.

[68] The first season and its accompanying OVA were also licensed by Madman Entertainment in Australia and New Zealand,[69] and by MVM Films in the United Kingdom.

[101] A weekly radio drama of Shakugan no Shana aired four episodes between November 29 and December 20, 2003 on Dengeki Taishō.

[103] Another drama CD was released with the April 2008 issue of Tokuma Shoten's Animage magazine; the cast is the same as with the anime versions.

[104] An action RPG visual novel titled Shakugan no Shana, developed by Vridge and published by MediaWorks, was released on March 23, 2006 for the PlayStation 2 (PS2).

The opening theme song is "Exist" by Rie Kugimiya, which was released on volume one of the Assorted Shana albums.

[92] The player assumes the role of Yuji Sakai during the visual novel aspect, where much of the game's duration is spent on reading the text that appears on the screen, which represents the story's narrative and dialogue.

Sometimes during text progression, an "active countdown" minigame appears, which requires the player to press the game buttons in a specific order in a set time limit.

The player uses a combination of fire, powers of unrestraint, and treasure tools to battle Crimson Denizens; and Shana is also able to use a special attack and defend.

"[116] When reviewing the anime, Martin thought the first Shakugan no Shana always manages to slightly exceed expectations, and while its story elements may be typical, its execution is not.

[117][118] Martin noted that Shana's Flame Haze transformation is a visual highlight of the series, and other details are shown equal care.

[122] The pacing in the middle of the first season was criticized for quickly ending an arc before "going into a storyline that feels out of character for the show.

"[123] Martin's review of Shakugan no Shana Final was less positive; he described Yuji as having been made into a different character (though his complexity was praised), criticized the addition of a large number of prominent characters without sufficient development, and described some things as not making sense, although he praised Shana's development over the course of the third series.