0verflow (オーバーフロー) (stylized 0verflow) is a Japanese video game division of Stack Ltd. (有限会社スタック) specializing in the production of mature interactive fiction. The Overflow label is known for its game franchise School Days. Stack's headquarters are located in the Sugishō Building (杉商ビル) in Kanda, Chiyoda, Tokyo. On February 10, 2012, Overflow confirmed that Shiny Days, a remake of Summer Days, will be the last title produced by the brand. The team also reassured customers that it was not going bankrupt and would continue to support their line of video games even after the release of Shiny Days.
Overflow's PureMail video game was adapted into a two-episode OAV in 2001.
Overflow's Imouto de Ikou! video game was adapted into a two-episode OVA in 2003.
Overflow's School Days video game was adapted into a 12-episode anime series in 2007. Both School Days and Cross Days have also received manga adaptations.
Stack's Welcome to Pia Carrot!! video game series was adapted into a three-episode hentai OVA from 1997 to 1998. Its sequel, Welcome to Pia Carrot!! 2 was adapted into a three-episode hentai OVA from 1998 to 1999, and a six-episode OVA titled Welcome to the Pia Carrot!! 2 DX from 1999 to 2000. The video game also received an anime film titled Welcome to Pia Carrot!! -Sayaka no Koi-monogatari- in 2002.
Overflow produced such games as:
- November 26, 1999: Large PONPON (らーじ・PONPON, Rāji Ponpon)
- August 25, 2000: PureMail
- April 27, 2001: 0verflow Pleasure Box (オーバーフローぷれじゃ～ボックス, Ōbāfurō Purejā Bokkusu)
- December 28, 2001: Snow Radish Vacation (Snowラディッシュバケーション, Sunō Radisshu Bakēshon)
- December 27, 2002: Let's go for the little sister! (妹で行こう!, Imōto de Ikō!)
- August 13, 2003: Summer Radish Vacation!! (Summerラディッシュバケーション, Samā Radisshu Bakēshon!!)
- December 27, 2003: Magical Unity (マジカル☆ユニティー, Majikaru Yunitī)
- April 30, 2004: MISS EACH OTHER
- October 15, 2004: LOST M
- April 28, 2005: School Days (スクールデイズ, Sukūru Deizu)
- January 27, 2006: 0verflow Premium Trilogy Box (オーバーフロープレミアムトリロジーボックス, Ōbāfurō Puremiamu Torirojī Bokkusu)
- June 23, 2006: Summer Days (サマーデイズ, Samā Deizu)
- March 19, 2010: Cross Days (クロスデイズ, Kurosu Deizu)
- October 8, 2010: School Days HQ (スクールデイズ ハイクオリティ, Sukūru Deizu Hai Kuoritī)
- April 27, 2012: Shiny Days (シャイニーデイズ, Shainī Deizu)
- July 3, 2014: Island Days (アイランドデイズ, Airando Deizu)
- April 28, 2016: Strip Battle Days 2 (ストリップバトルデイズ2, Sutorippu Batoru Deizu 2)
- TearMail (cancelled)
Stack was involved in games such as:
- July 26, 1996: Welcome to Pia Carrot (MS-DOS)
- October 18, 1996: Welcome to Pia Carrot!! (Windows)
- May 23, 1997: Welcome to Pia Carrot!! (PC-FX)
- October 31, 1997: Welcome to Pia Carrot!! 2 (Windows 95)
- March 12, 1998: Welcome to Pia Carrot!! (Sega Saturn)
- October 8, 1998: Welcome to Pia Carrot!! (Sega Saturn)
- December 2, 2000: Welcome to Pia Carrot!! 2.2 (Game Boy Color)
- June 21, 2001: Welcome to Pia Carrot!! 2.5 (Dreamcast)
- October 26, 2001: Welcome to Pia Carrot!! 2 (Windows Me/2000)
- November 30, 2001: Welcome to Pia Carrot!! 3 (Windows 95/98/Me/2000)
- February 6, 2003: Welcome to Pia Carrot!! 2 (Dreamcast)
- March 27, 2003: Welcome to Pia Carrot!! 3 (Dreamcast), (PlayStation 2)
- April 23, 2004: Welcome to Pia Carrot!! 3 (Game Boy Advance)
- 2006: Welcome to Pia Carrot!! G.O. ~Grand Open~
- 2006: Pia Carrot G.O. TOYBOX ~Summer Fair~
- 2007: MahJong in Pia Carrot~
- 2008: Welcome to Pia Carrot!! G.P.
- 2009: Welcome to Pia Carrot!! 4
- 2010: Pia Carrot 4 FD
- 2014: PriPia ~Prince Pia Carrot~