13 Where's fourth?

(10/23/19)

knock, knock, knock, three different sounds

three doors, three walls, choose one

left door, the past

middle door, the present

right door, the future

hmm? choose or not?

it is up to you, believing it or not

you want a fourth one?

if you're reading this 'inside' of the book

the 'outside' is your choice, hehe~