TL;DR
Should you pull on this banner now? Consider your needs and pity.
Who is Matsumoto Kouko?
Matsumoto Kouko is a character from Watashi Ni Tenshi Ga Maiorita!. She is an N rarity character and has unique abilities. Her skills and strengths make her a valuable addition to any team. As a character from a popular anime, she has a dedicated fan base.
When to pull — daily-free pulls vs paid pulls, hard-pity math
When deciding whether to pull, consider your daily-free pulls and paid pulls. Hard-pity math also plays a role, as you have a guaranteed pull after a certain number of attempts. If you are close to the pity threshold, it may be worth pulling to guarantee the character.
10x vs single pull math at this rarity tier
At the N rarity tier, the math for 10x pulls versus single pulls is important. Generally, 10x pulls give you a better chance of getting the character you want, but they also cost more. Single pulls, on the other hand, are cheaper but have a lower success rate. Consider your budget and goals when deciding which type of pull to use.
What if she's a duplicate — trade vs master vs unlock
If you already have Matsumoto Kouko and pull her again, you have a few options. You can trade the duplicate for other characters or items, master her to increase her power, or unlock new abilities. Consider what is best for your team and strategy.
My recommendation
Based on the current banner and pity system, I recommend pulling for Matsumoto Kouko if you need an N rarity character. Consider your budget and goals, and use the pity system to your advantage. If you already have her, weigh the options for duplicates and decide what is best for your team.