there might be alot of internal feelings involved in what he sees here.
he might have felt his father to be a fluffy character, never really approaching him, but overall being comfy. he might have subconciously felt his mother always looking at him with two eyes, the one trying to be the mother and the one that struggled to see him for what he is. his strong maid got the oni horn, his fiancee which he shared many letters with got the pen. his teacher being a powerful being much like the sun and his aid being the powerful heroic being. though i'm clueless about the crab, maybe he sees himself being an odd fella, so he got an odd follower that spews bubbles and is affiliated to water?
and to be fair it wouldn't be odd for him to see things differently since he had to come up with the whole world and colors on his own. but i bet there's some deeper meaning involved here as well.