Amtrakster:
I suggest readins an excellent book on the subject called "At Dawn we Slept".
It seems to be THE reference for the attack on Pearl harbor.
In this book, they refer to the Mini-Sub attack, in detail. So much so as to give their tender subs, crews, missions, and locations. The Japanese mentality at the time was simple. Do evrey thing you can to hit your target, and try to survive. They went with little fear of death, but they were in no way suicidal. Many expressed great relief in their personal diaries for surviving the raid, and being able to see their families again.
At the pre-flight briefing, the commander of the mission (his name escapes me) was asked what he would do if his plane was disabled. He said he would crash into a target instead of being captured. He stressed that he would not ask any of his pilots to do the same.
As for the Mini-sub, the only one of the four we know about that could be classified suicidal would be the 3rd launch, which left it's mothership with a faulty gyro. That crew was pretty sure they would not return, but wanted to hit their targets anyway.
So, in summation, I am of the opinion from what I've read that the mentality of the IJN was not one of suicide, but of acceptance of a High-Risk mission.
Sorry for the HiJack