Employee benefit plans (Tables)

6 Months Ended

Sep. 30, 2017

Employee benefit plans

Net periodic benefit cost of defined benefit plans

	Millions of yen
	Six months ended September 30
	2016			2017
Service cost	¥	4,459		¥	5,018
Interest cost		722			1,129
Expected return on plan assets		(3,002	)		(3,033	)
Amortization of net actuarial losses		1,424			2,003
Amortization of prior service cost		(574	)		(530	)
Net periodic benefit cost	¥	3,029		¥	4,587
	Millions of yen
	Three months ended September 30
	2016			2017
Service cost	¥	2,098		¥	2,393
Interest cost		361			564
Expected return on plan assets		(1,501	)		(1,517	)
Amortization of net actuarial losses		712			1,001
Amortization of prior service cost		(287	)		(265	)
Net periodic benefit cost	¥	1,383		¥	2,176