Why?

Well it seems your suffering would be quite longer. March or probably late Feb would be the rerun of GudaGuda honnoji so patiently wait. Quite a few months, I say.

Trust me I know your pain I missed out on so many events since I started on sabers wars (luckily all the events I missed have reruns) and like Ruzeron said the rerun is early next year so just stay strong and work on getting all her skils to 10.

I feel you mate but atleast you have her. Started since onigashima and miss the fate zero event, now i will never have a chance to get Irismama again...

Starting playing during a major event that offers a free NP5 servant almost always results in this outcome. I started playing during Counterfeit Spirits event, aka Jalter. Did I roll a Jalter? Did I understand the game well enough to even want her? No. I did roll Iskandar NP2 on the following banner, which also had Waver on rate up. He is a very effective offensive support for my Raikou. I don't even bother using his main self-buff skill. I used Irisviel extensively this event as a caster tank. Get Raikou ready to fire, activate her buffs, swap in Iskandar and activate his first two skills, bye bye ANY wave. Not being able to get all copies and ascension materials is common when it's your very first event. None of my event servants are even fully ascended yet. I have them all at NP5 with all materials, but when you have 24 gold servants and a handful of silver ones you care about, it's very difficult to obtain enough resources to maximize their effectiveness.

I look forward to the reruns of free servants I missed because I started playing too late. I do not have Nobu and so we are in the same boat. ;)

Your name just makes me think of Hanebado even though there are other ayanos in anime and in the world

Does Assassin shiki event get a rerun?

I feel your pain. I got Nobu up to lv 4 NP, but I can't ascend her because I don't have any Golden Skulls.