Cerberus (Fukuyama Kentarou)

[Thelemic Potter]

So I've folded everything to step 38, finally got it to collapse down to the outline seen in 39, but it won't fold flat by step 40. I went and drew in all the mountain/valley lines and checked again, still nothing. I'm suspecting that there is something in the Japanese titles in these steps that might clarify what is going on here. Hopefully someone around here has a translation that will aid me, if not, some other advice.