2019 Keio Challenger – Men's singles

Yasutaka Uchiyama was the defending champion but chose not to defend his title.

Kwon Soon-woo won the title after defeating Oscar Otte 7–6(7–4), 6–3 in the final.

Seeds
All seeds receive a bye into the second round. • # 🇯🇵 Tatsuma Ito (third round)

• # 🇩🇪 Oscar Otte (final)

• # 🇯🇵 Yūichi Sugita (semifinals)

• # 🇯🇵 Hiroki Moriya (second round)

• # 🇩🇪 Mats Moraing (third round)

• # 🇦🇹 Jurij Rodionov (third round)

• # 🇯🇵 Go Soeda (third round)

• # 🇮🇱 Dudi Sela (quarterfinals)

• # Blaž Rola (third round)

• # 🇮🇹 Gianluca Mager (quarterfinals)

• # 🇰🇷 Kwon Soon-woo (champion)

• # 🇦🇷 Pedro Cachin (second round)

• # 🇧🇷 Guilherme Clezar (second round)

• # 🇨🇦 Filip Peliwo (third round)

• # 🇷🇸 Viktor Troicki (second round)

• # 🇫🇷 Enzo Couacaud (second round)