Question: Which video game published by Sega in 2001 was the sequel to a video game developed by Ys Net?

Context paragraphs:
Ys: The Ark of Napishtim: Ys: The Ark of Napishtim (イースVI -ナピシュテムの匣- , Īsu Shikkusu -Napishutemu no Hako- ) is an action role-playing video game developed by the Nihon Falcom, and the sixth installment in the "Ys" video game series.  It was first released in 2003 for Microsoft Windows.  Not counting the Eternal/Complete remakes of "Ys I" & "II", it was the first new "Ys" game released by Falcom in eight years.  The name "Napishtim" is a reference to the character Utnapishtim from the "Epic of Gilgamesh".

Shenmue (series): Shenmue (Japanese: シェンムー , Hepburn: Shenmū ) is an open-world action-adventure video game series created, produced and directed by Yu Suzuki. " Shenmue" and "Shenmue II" were developed by Sega AM2 and published by Sega for Dreamcast on December 29, 1999, and September 6, 2001 respectively; "Shenmue II" was ported to Xbox in 2002. " Shenmue III," developed by Suzuki's company Ys Net, is due for release in the second half of 2018 for PlayStation 4 and PC.  Suzuki plans the series to span at least four games.

Shenmue II: Shenmue II (Japanese: シェンムー II , Hepburn: Shenmū Tsū ) is an open-world action-adventure video game developed by Sega AM2 and published by Sega for the Dreamcast in 2001.  It was directed, produced and written by Yu Suzuki.  It is the second game in the "Shenmue" series, a "revenge epic in the tradition of Chinese cinema", which Suzuki plans to cover at least four games.

Ys IV: Mask of the Sun: Ys IV: Mask of the Sun (イースIV - Mask of the Sun - , Īsu Fō ) is an action role-playing video game developed by Nihon Falcom, and is the fourth game in the Ys video game series.  Ys series creators Nihon Falcom licensed its development to Tonkin House.

Super Monkey Ball (video game): Super Monkey Ball is a 2001 platform party video game developed by Amusement Vision and published by Sega.  The game debuted in Japan at the 2001 Amusement Operators Union trade show as Monkey Ball, an arcade cabinet running on Sega's NAOMI hardware and controlled with a distinctive banana-shaped analog stick.  Due to the failure of Sega's Dreamcast home console and the company's subsequent restructuring, an enhanced port dubbed "Super Monkey Ball" was released as a launch title for the GameCube in late 2001, garnering interest as Sega's first game published for Nintendo hardware.

Ys II: Ancient Ys Vanished – The Final Chapter: Ys II: Ancient Ys Vanished - The Final Chapter (イースII , Īsu Tsū ) is an action role-playing video game developed by Nihon Falcom, and first released on June 24, 1988 for the PC-8801 and PC-9801.  It is the sequel to "", and takes place immediately following the end of the first game.  It was released along with its predecessor as part of the enhanced compilation, "Ys I & II", for the TurboGrafx-CD in 1989.  It was later adapted into the anime "Ys II: Castle in the Heavens" (1992).

Shenmue III: Shenmue III is an upcoming action-adventure role-playing video game developed by Neilo and Ys Net and published by Deep Silver, scheduled for release in the second half of 2018 for Microsoft Windows and PlayStation 4.  It is directed, written and produced by series creator Yu Suzuki, and follows teenage martial artist Ryo Hazuki in his quest to find his father's killer in 1980s China.

Ys Seven: Ys Seven (イース7 ) is an action role-playing video game developed by Nihon Falcom and the seventh installment in the "Ys" video game series.  It was released in Japan during 2009 for the Sony PlayStation Portable and was released by XSEED Games in North America on August 17, 2010, in Europe on November 3, 2010 and in Australia on February 20, 2013.  The game was released for Microsoft Windows in China on June 20, 2012, and worldwide on Steam in August 2017.

Ys VIII: Lacrimosa of Dana: Ys VIII: Lacrimosa of Dana (Japanese: イース VIII -Lacrimosa of DANA- ) is an action role-playing video game developed by Nihon Falcom and is the eighth installment in the "Ys" video game series.  It was released in Japan on July 21, 2016 for PlayStation Vita and for PlayStation 4 on May 25, 2017.

Ys IV: The Dawn of Ys: Ys IV: The Dawn of Ys (イースIV -The Dawn of Ys- , Īsu Fō ) is an action role-playing video game developed for the PC Engine CD-ROM², and is the fourth game in the Ys video game series.  Ys series creators Nihon Falcom Corporation licensed its development to Hudson Soft.

Supporting paragraphs: Shenmue (series) Shenmue II
Answer: Shenmue II