I read that tight spaces could be extremely calming and mind-emptying, for people with severe headaches just sitting in the bathroom (in the dark) can help
i think her tight spaces thing might be an allusion to an autistic quirk of sorts. she does seem to tend to have some autistic tendencies and might be intended to legitimately be autistic (though manga characters never act like real humans so if thats the intention its obviously not very realistic)
@wanderingwarrior97 odajima's "thing" is that its kept unclear if she likes ohta or not. gets further developed in later chapters (i have it read/tld up to 43)
I like sleeping in cramped places like sofas and bury myself in pillows,
But I'll never understand the enjoyment in getting stuck between a wall and the lockers