Ikkyo
Its called the first teaching and is a foundation technique for art. For many its just an armbar but scratching below the surface we find so much more. With its roots in the old koryu arts we can return to sword exercises to gain some fundamental understanding, have a look at its purpose on the battle field and then see how its been modified for uke (see Origins of Ikkyo). Along the way we discover that then are more than a few exit points and that periodically returning to the sword can be helpful.
Put through its paces with Maruyama Sensei's five levels of technique ( Kontai - Seeking the soul of Aikido) we get as new look at what Irimi nage might look like if we do the ikkyo kata (and have a sneak peak at nikkyo, sankyo and yonkyo for irmi nage as well). Actually Kutai and Kontai are my interpretation until Maruyama Sensei covers it formally...hopefully soon. See also Origins of Ikkyo
Brief notes...full text to follow
Kotai
proper distances and positioning
one uke attacks they cannot attack further
nage has opportunities for atom at multiple points
moon shadow foot and lizard legs are training tools to learning proper positioning
focus is still on cutting ukase centre as if with a sword
Jun tai
following level. nage moves just in front of ukase movement. uke follows nags movement. both are learning their parts in the kata. Nage the technique and uke the suppleness required to received at more dynamic levels
Ryutai
freestyle. attacks can come from many angles and places and just apply icky principe to pin uke
Kutai - universe level
introduces the principle of moving in large circles (like the universe) as a way point to getting to kontai. progressively reduce the circle size to a point to get kontai
Kontai
use the icky principle of getting off the line and cutting down. the technique manifests like iriminage but everything else is icky kata
have similar ideas for 2,3,4 teaching. To understand have to decouple the icky component seen in these kata at lower level. Thus Nikkyo (broken timing of drawing in and sending back), Sankyo (cutting up through uke's centre), Yonkyo(cutting through uke)