Vdic form

MNN18-1

It's the dictionary form look it up!

Can be backformed from masu.
drop ます
go from い row to う row for v5 (group1) いきます → いく
add る for v1 (group2) みます→ みる

Knowing both the dic-form and the masu-form should clarify verb groups.
eg.
おきます → おきる → to get up v1 (group2)
おきます → おく→ to press v5 (group1)

This is essentially why you should start from the dictionary form, knowing the group and if a verb is transitive or intransitive.