All kata are bunkai

We practice martial arts that are forms of abstracted combat. This abstraction is unavoidable because practicing ‘real’ combat either leads to unacceptable rates of attrition (you lose ½ of your training partners at the conclusion of each fight) or it leads to unacceptable moral and social conduct (you waylay and kill innocent passers-by). Without the abstraction there is no way to systematically improve.
The abstractions that change combat into martial art involve various sets of rules of conduct between participants who explore different models of combat-like situations. Because any model is necessarily incomplete, we work with multiple different models. These models include:

• Kihon – fundamentals
• Kata – patterns and principles
• Bunkai – break-down analysis of kata
• Henka/Renraku/Kaeshi – Variation/Combination/Reversal techniques
• Kumite – engagement matches
• Randori – exploring freedom
• Makiwara – test striking/cutting real objects

In some martial arts (i.e. karate-do) the kata are performed solo, which necessitates other models like makiwara, bunkai, and kumite. Aikido and judo kata are interesting because they are always performed with a partner and they include aspects of the kata, bunkai, and kumite combat models. In aikido all kata are bunkai.