"Sunny Sunny Delight") is the ending theme song to the 2006 anime adaptation of The Melancholy of Haruhi Suzumiya (the first book in the Haruhi Suzumiya light novel series by Nagaru Tanigawa and several other short stories).

It was released as a physical single of the same title on May 10, 2006 by Lantis with the B-side "Welcome Unknown", the ending theme song to the radio show The Melancholy of Haruhi Suzumiya: SOS Brigade Radio Division that was also performed by the same actresses.

The popularity of the song also led to growing interest in the Japanese voice acting industry.

"Hare Hare Yukai" is the ending theme song from the 2006 anime series The Melancholy of Haruhi Suzumiya (the animated adaptation of the first book and several short stories in the Haruhi Suzumiya series by Nagaru Tanigawa).

[1] The vocals are performed by voice actresses Aya Hirano, Minori Chihara, and Yuko Goto, who portray the characters Haruhi Suzumiya, Yuki Nagato, and Mikuru Asahina respectively.

[2] The B-side of the single, "Welcome Unknown", also performed by the same actresses, was used as the ending theme song to The Melancholy of Haruhi Suzumiya: SOS Brigade Radio Division, a promotional radio show for The Melancholy of Haruhi Suzumiya.

[17] Aya Hirano, Minori Chihara, and Yuko Goto, the voice actresses of Haruhi, Yuki, and Mikuru, revealed the choreography to the full version of "Hare Hare Yukai" to the public when they performed the song at the 2006 Animelo Summer Live.

[20] By July 2006, it sold over 100,000 copies and earned a Gold certification from the Recording Industry Association of Japan.

[25] On March 18, 2007, they performed the song again with Tomokazu Sugita (the voice actor of Kyon) and Daisuke Ono (the voice actor of Itsuki Koizumi) at The Extravagance of Haruhi Suzumiya, a live concert event for the cast of The Melancholy of Haruhi Suzumiya.

[34] "Hare Hare Yukai", along with Nana Mizuki's 2005 song "Eternal Blaze", was also credited for inspiring the "voice actor boom" in the mid-2000s, where the release of the songs led to more public interest in the Japanese voice acting industry.

[34] On April 24, 2020, Hirano posted a video of herself dancing and teaching the choreography of "Hare Hare Yukai" on her social media accounts to motivate others during the height of the COVID-19 pandemic, sparking the hashtag "#HareHareYukaiAtHomeWithAllYourMight" (#お家で全力ハレ晴レユカイ).

[50] The song was used as the fourth ending theme for the 2024 anime series Alya Sometimes Hides Her Feelings in Russian covered by Sumire Uesaka.