Boob sweat? Lactation?
>>14571514
Ok, I know this may be a shocker to you, but skin touching skin accumulates the naturally occuring sweat. Since larger breasts have a larger area touching the chest area, this makes even more sweat, which in turn causes rash in the lower side of the breast.
>>14571539
But she has small breasts. And it's not where the skin is touching.
>>14571596
May be a glandular issue.
>>14571603
If only that had been explored in Makina's route
>>14571514
The show picked the right choice.