Nagakute is one of the scenarios in the board game ‘Ran’ from GMT. There is a vassal module for that which you could derive a map from.
The numbers given in the Nihon Senshi series by the Imperial Japanese Army General Staff in 1908 for the battle are probably dubious. But that gives:
Tokugawa army:
Right wing under Ieyasu: 3,300
Left wing under Ii Naomasa: 3,000
Centre under Oda Nobuo: 3,000
Mori-Ikeda army:
Right wing under Ikeda Motosuke and Ikeda Terumasa: 4,000
Left wing under Mori Nagayoshi: 3,000
Rear under Ikeda Tsuneoki: 2,000