2023 Keio Challenger

The 2023 Keio Challenger was a professional tennis tournament played on hard courts. It was the 16th (men's) and 6th (women's) editions of the tournament and part of the 2023 ATP Challenger Tour and the 2023 ITF Women's World Tennis Tour. It took place in Yokohama, Japan between 20 November and 3 December 2023.

Seeds

 * 1 Rankings are as of 13 November 2023.

Other entrants
The following players received wildcards into the singles main draw:
 * 🇯🇵 Masamichi Imamura
 * 🇯🇵 Rio Noguchi
 * 🇯🇵 Rei Sakamoto

The following player received entry into the singles main draw as an alternate:
 * 🇹🇷 Altuğ Çelikbilek

The following players received entry from the qualifying draw:
 * August Holmgren
 * 🇲🇰 Kalin Ivanovski
 * 🇦🇺 Omar Jasika
 * 🇯🇵 Naoki Nakagawa
 * Colin Sinclair
 * 🇯🇵 Yasutaka Uchiyama

The following players received entry as lucky losers:
 * 🇰🇷 Chung Yun-seong
 * 🇫🇷 Mathys Erhard
 * 🇮🇹 Giovanni Fonio

Men's singles

 * 🇯🇵 Yosuke Watanuki def. 🇯🇵 Yuta Shimizu 7–6(7–5), 6–4.

Women's singles

 *  Aliona Falei def. 🇯🇵 Ayano Shimizu, 6–3, 7–5

Men's doubles

 * 🇸🇪 Filip Bergevi / Mick Veldheer def.  Ray Ho / 🇦🇺 Calum Puttergill 2–6, 7–5, [11–9].

Women's doubles

 * Liang En-shuo / 🇨🇳 Tang Qianhui def. 🇯🇵 Aoi Ito / 🇯🇵 Natsumi Kawaguchi, Walkover