This chapter is temporally confusing to me. They're wearing their short sleeved summer uniforms, and the last time those showed up was chapter 39 (though oddly 35 and 38 also lacked them before the full switch). They go back to long sleeves next chapter. Which I guess maybe means this one took place a while before? Who know.
Even as far as the events themselves it feels like something that should have come a lot earlier, though even the 28-39 stretch still seems a bit late.