By the way, is there a rule to how these short forms are formed?
Yep! Most Japanese verbs (with a few exceptions like ‘shimasu’ becoming suru) use one of the ‘i’ variants (‘i’, ‘ki’, ‘ni’, ‘mi’, or ‘ri’) after the kanji, that indicates they are verbs.
Ki will become ku in the shortened version, ri will become ru, ni -> nu, etc:
yaku, shiru, aruku, aru, shinu, yomu
I believe the verbs that don’t end in one of those like tabemasu (to eat) will default to ‘ru’ (taberu), but I don’t know if that’s a rule off the top of my head, or if I just can’t think of any others right now.
In the cases where rendaku applies, such as oyogimasu (to swim), the end kana will also have rendaku applied, e.g. oyogu. Ki -> ku, gi -> gu.
Fascinating. That explains the similarity. Since watching that episode of Witch Watch I definitely feel bad about my formal “Duolingo” Japanese :D
By the way, is there a rule to how these short forms are formed?
Yep! Most Japanese verbs (with a few exceptions like ‘shimasu’ becoming suru) use one of the ‘i’ variants (‘i’, ‘ki’, ‘ni’, ‘mi’, or ‘ri’) after the kanji, that indicates they are verbs.
Yakimasu (to burn/ cook), shirimasu (to know), arukimasu (to walk), arimasu (to be), shinimasu (to die), yomimasu (to read).
Ki will become ku in the shortened version, ri will become ru, ni -> nu, etc:
I believe the verbs that don’t end in one of those like tabemasu (to eat) will default to ‘ru’ (taberu), but I don’t know if that’s a rule off the top of my head, or if I just can’t think of any others right now.
In the cases where rendaku applies, such as oyogimasu (to swim), the end kana will also have rendaku applied, e.g. oyogu. Ki -> ku, gi -> gu.