The date is a pun:
Shizuha → shi(4) zu(→tsu →2 —English-like pronunciation) ha(8)
The goddess of red leaves, who conscientiously paints them all one by one at the turn of Fall (she seems to have complicated feelings for her little sister, the goddess of harvest)
Even though I should be above average...My sister seems to be the one attracting all the attention...Today was pretty warm, wasn't it, sis?