枕

1. Origins, structure, and basic meaning

• Structure: 枕 is read as まくら and is a noun for a pillow used to support the head during sleep.
• Basic usage: 柔らかい枕に替える names the replacement, while 小さな枕を持って行く makes the pillow the item carried.

2. Common pitfalls and similar expressions

• Result marked by に
  • In 枕に替える, に identifies what the previous pillow or arrangement is changed to.
• Object marked by を
  • The travel pillow is the object being taken, so it takes を with 持って行く.