You were certainly there for the hatazirushi event, as you were on my friends list well before the event started. It's possible that you weren't yet strong enough to beat the opponents that drop it. It's also decently likely that you could have gotten the item but didn't realize that it was a really nice item and should have been your top priority in what to do while playing during the event until you got one.
There were two opponents that could drop it, with one substantially stronger than the other, and you could only beat them each 30 times per day. The hatazirushi had a drop rate of about 0.5%, so it could easily take several days to get one. But there are far more opponents that you can fight each day than you actually have time to fight, so you have to find the best ones.
In the case of the hatazirushi, I looked it up on the Japanese wiki, which is linked at the start of this thread. I don't know Japanese, and Google translate often comes out fairly garbled. But while you can't count on the name on the Japanese wiki matching the English version, the icons are always identical. From the item effects on the Japanese wiki, it looked like the item (which Google translates as something like "banner flag") might be really nice, so I fought the opponents that drop it until I got one.