[Guest]

As far as I know (and I may be wrong. In fact, I kinda hope I am) the pilot climbed in before the Ohka was attached to the betty and he was locked in his cockpit from the outside.
I don't know if they used locks, bolts, glue or soldering and I don't want to know.

the position of the Ohka when attached to the betty seem plausible to me, and it matches the external view .