The other main group of Japanese verbs, u-verbs, are slightly more complicated that ru-verbs. The suffix of u-verbs is u. For the verb いく (iku) “to go”, the u is removed, leaving the stem ik. Like ru-verbs, the endings ーます (masu) and ーません (masen) are added, but with an i before each of the endings. To remember the i before the endings, think of the stem as いき (iki):
Dictionary Form いく (iku)
Stem いき (iki)
Present, Affirmative いきます (ikimasu)
Present, Negative いきません (ikimasen)
Some verbs that end in る (ru) can be u-verbs, such as かえる (kaeru) “to return”:
Dictionary Form かえる (kaeru)
Stem かえり (kaeri)
Present, Affirmative かえります (kaerimasu)
Present, Negative かえりません (kaerimasen)
Before conjugation, it is important to know which type of verb you are using.