Persona 4: Golden Tips

Acquire the Fishing Pole
Speak to the old man at the Samegawa Flood Zone riverbank during the day to find that his Fishing Hook has gone missing.

Speak to the boy at the Shrine Central Shopping District (North) and find out what food or drink he is currently craving; acquire the appropriate item at any vending machine or the Sozai Daigaku food stall in the Shopping District and give it to the boy to receive some Tatsuhime Ladybug(s) in return.

Venture into any dungeon in the Midnight Channel TV world and acquire unique gems (e.g. iolite, smokey quartz, etc.) as rewards from random encounters with Shadows.

Head to the Shiroku convenience store anytime at night when it transforms into a snack bar; the store owner will be willing to speak with you once you have any variety of gems. This also unlocks the option to trade these gems in for unique weapons. Talk to the owner and offer to feed her pet fish one of your Tatsuhime Ladybugs to receive the Fish Hook.

Bring the Fishing Hook back to the old man at the riverbank to at last receive the Fishing Pole!