Men's singles
2018 Keio Challenger
Final
Champion	Yasutaka Uchiyama
Runner-up	Tatsuma Ito
Score	2–6, 6–3, 6–4
Events
Singles men women Doubles men women
← 2017 · Keio Challenger · 2019 →

Yūichi Sugita was the defending champion but chose not to defend his title.

Yasutaka Uchiyama won the title after defeating Tatsuma Ito 2–6, 6–3, 6–4 in the final.

	Semifinals							Final
	1	Jordan Thompson	4	5
		Yasutaka Uchiyama	6	7
									Yasutaka Uchiyama	2	6	6
								7	Tatsuma Ito	6	3	4
		Cem İlkel
	7	Tatsuma Ito	w/o

	First round							Second round							Quarterfinals							Semifinals
	1	J Thompson	2	6	6
		P Gunneswaran	6	4	3			1	J Thompson	6	6
	Q	Hiroyasu Ehara	710	61	6			Q	H Ehara	4	2
		A Whittington	68	77	4										1	J Thompson	6	4	6
	LL	D Nguyen	6	6											5	S Robert	3	6	2
	WC	Yo Watanuki	2	4				LL	D Nguyen	5	0
	Q	Jumpei Yamasaki	6	1	3			5	S Robert	7	6
	5	S Robert	3	6	6																	1	J Thompson	4	5
	4	G Soeda	6	6																			Y Uchiyama	6	7
	WC	Kaito Itsusaki	0	2				4	G Soeda	77	6
		D Wu	6	77					D Wu	65	3
		Ze Zhang	4	65											4	G Soeda	6	60	3
		Y Uchiyama	6	3	6											Y Uchiyama	4	77	6
		H Hurkacz	4	6	4				Y Uchiyama	6	7
	WC	S Hazawa	6	4	77			WC	S Hazawa	3	5
	6	S-w Kwon	3	6	65

	First round							Second round							Quarterfinals							Semifinals
	8	D-h Lee	4	6	6
		T Pütz	6	4	3			8	D-h Lee	2	6	65
	SE	B Ellis	3	4					C İlkel	6	2	77
		C İlkel	6	6												C İlkel	77	6
		M Donati	711	2	5											T Kamke	63	2
		T Kamke	69	6	7				T Kamke	6	6
	Q	Y-s Chung	2	78	4			3	J Jung	4	2
	3	J Jung	6	66	6																		C İlkel
	7	T Ito	6	6																		7	T Ito	w/o
	WC	K Uesugi	2	3				7	T Ito	3	6	77
		J Kubler	6	1	6				J Kubler	6	3	63
		E Leshem	3	6	3										7	T Ito	6	6
		K Kravchuk	0	2											Q	H Moriya	3	3
	Q	H Moriya	6	6				Q	H Moriya	w/o
		M Purcell	3	67				2	J Millman
	2	J Millman	6	79

• Main draw
• Qualifying draw