Technically one single character cannot be tsundere and yandere at the same time, because yandere means honesty with obsession and tsundere means love but denial. Youmu here is honest about her love but also demands her bf/gf will only look at and love her (after all she does the same).
Ehh...
Y-You're late! Way too late!
Did you ever think about how long I've waited!?
I-It's not like you didn't know...
How much I yearned for you, right...
You've kept me waiting long enough!T-Therefore!
From here on... p-please look only at me!
I've also always...!