Even early in Sekiro: Shadows Die Twice, there are some tough battles to deal with, but they can be made much easier with the right weapons and items. There are a bunch of early prostheses that you should not miss, like Flame Vent, which can be a great help in fighting Chained Ogre. Lady Butterfly, a fast-paced boss who uses illusory apparitions to help her, is another giant who is much easier if you have the right equipment.
Managing Lady Butterfly is much easier if you have Snapseeds, a consumer product that breaks the illusion of the boss's perceptions. You get a Snapsed from a samurai just outside the room where you fight Lady Butterfly, but it runs pretty fast. Snapseeds are not essential to defeating Lady Butterfly, but they make the game much easier. The problem is that Snapseeds are hard to come by and are only in certain places, and you can't buy them from merchants.
You can quickly find Snapseeds to fight Lady Butterfly if you know where to look. Tracking them down requires you to head back to the Ashina edge and deal with another tough enemy: the white snake.
To find Snapseeds, start by going to the Underbridge Valley area of Ashina Outskirts. You will find the place soon after beating the Chained Ogre boss. As you walk past the Idol statue of the place, you will encounter the giant white snake, a massive boss, chasing you throughout your passage through the area.
The trick to passing the white snake is stealth. Get low and hidden in the tall grass, wait until the snake's attention is elsewhere, then jump over the valley and use your grip to get ready. Repeat the process of sneaking and avoiding the hose until you reach the tree palanquin, where you can briefly hide from the hose. When it comes close to trying to look inside, you can make a death blower on the eye, causing it to clap in horror and pain, allowing you to drive for the exit of the outside area.
When you are free from the snake, hit the Ashina Castle Gate Fortress and its corresponding Idol Statue. Do not continue when you get there. Instead, double back to where you fought the snake. You should see a glowing object on the hill next to palanquin where you stacked the white snake and marked a bush on the hillside. Head to it and you can grab five snapseds from the bush.
It is advisable that you spend some time fighting Lady Butterfly before using your Snapseeds. The perceptions that you do not destroy with your sword or with the seeds turn into ethereal butterflies that can hurt you, but they are easy to dodge or block with the wooden beams around the area. If you use Snapseeds, make sure you are close to apparitions before you activate them – they create a wave around you that burst the ghosts, but if you are too far away, it doesn't work.