After you have done some missions Tsunade will give you the mission
once you enter her office. When you got it just walk to the Sand
village, teleports will be disabled. On the way there she will
interrupt you with a few talking sessions. When you arrive at the
Sand village go to the last street area to meet with 2 people
standing around there. Tsunade will order you to get to get to the
desert and organize a item for her. Leave the village and go to the
Overlapping Deserts Area [13] and check the upper right pit for a
flower. When you walk back to the Sand village and you will see
that the number of bandits has increased so you will have to do
a few fights. Bring the item to Tsunade and afterwards head with
her to the Akatsuki Cave [26] and enter it. Tsunade will talk a bit
more and then you have to get the medicine she dropped. You can
find it at the west part of the river. Go back and give the item to
her. Some more talk will happen and when you're outside of the
Akatsuki Hideout a ninja from Konoha will tell Tsunade that she is
needed back home and she will leave. Mission is over now.