The Hayabusa 2 mission is targeted to explore the asteroid (162173) 1999 JU3 and return surface as well as sub-surface samples through a novel impactor. Upon its return, at the end of 2020, the spacecraft will release the capsule for Earth re-entry and drift away from the planet. Based on the current mission profile, the spacecraft is expected to retain 30 kg of xenon propellant for trajectory maneuvers after the capsule is released. This remaining fuel can be used to extend the mission and improve its scientific return by exploring a new target. Work herein outlines an extension plan for Hayabusa 2, detailing the target selection process and its subsequent trajectory design. Due to final Earth escape trajectory, considering the excess velocity and orbital geometry, the only available extension option is an asteroid flyby. One of the most important trajectory characteristic is to maximize the spacecraft's optical detection capabilities. As a result the asteroid 2001 WR1 is identified as the most promising target candidate. The resulting trajectory uses all the available xenon with 100% duty cycle. Furthermore, the extension lasts for 932 days and offers 1.57 days of optical navigation time for a flyby on June 27, 2023.